diff --git a/src/bots/approved_bot/mod.rs b/src/bots/approved_bot/mod.rs
index 99125f7..597ae3a 100644
--- a/src/bots/approved_bot/mod.rs
+++ b/src/bots/approved_bot/mod.rs
@@ -3,6 +3,7 @@ pub mod services;
 mod tools;
 
 use moka::future::Cache;
+use smallvec::SmallVec;
 use teloxide::{prelude::*, types::BotCommand, adaptors::{Throttle, CacheMe}};
 
 use crate::{bots::approved_bot::services::user_settings::create_or_update_user_settings, bots_manager::AppState};
@@ -23,7 +24,7 @@ async fn _update_activity(
     me: teloxide::types::Me,
     user: teloxide::types::User,
     activity_cache: Cache<UserId, ()>,
-    user_langs_cache: Cache<UserId, Vec<String>>,
+    user_langs_cache: Cache<UserId, SmallVec<[String; 3]>>,
 ) -> Option<()> {
     if activity_cache.contains_key(&user.id) {
         return None;
diff --git a/src/bots/approved_bot/modules/book.rs b/src/bots/approved_bot/modules/book.rs
index 1296fd2..2fcd928 100644
--- a/src/bots/approved_bot/modules/book.rs
+++ b/src/bots/approved_bot/modules/book.rs
@@ -3,6 +3,7 @@ use std::str::FromStr;
 
 use moka::future::Cache;
 use regex::Regex;
+use smallvec::SmallVec;
 use teloxide::{dispatching::UpdateFilterExt, dptree, prelude::*, adaptors::{Throttle, CacheMe}};
 
 use crate::{bots::approved_bot::{
@@ -118,8 +119,8 @@ async fn send_book_handler<T, P, Fut>(
     message: Message,
     bot: CacheMe<Throttle<Bot>>,
     command: BookCommand,
-    books_getter: fn(id: u32, page: u32, allowed_langs: Vec<String>) -> Fut,
-    user_langs_cache: Cache<UserId, Vec<String>>,
+    books_getter: fn(id: u32, page: u32, allowed_langs: SmallVec<[String; 3]>) -> Fut,
+    user_langs_cache: Cache<UserId, SmallVec<[String; 3]>>,
 ) -> crate::bots::BotHandlerInternal
 where
     T: Format + Clone + Debug,
@@ -190,8 +191,8 @@ async fn send_pagination_book_handler<T, P, Fut>(
     cq: CallbackQuery,
     bot: CacheMe<Throttle<Bot>>,
     callback_data: BookCallbackData,
-    books_getter: fn(id: u32, page: u32, allowed_langs: Vec<String>) -> Fut,
-    user_langs_cache: Cache<UserId, Vec<String>>,
+    books_getter: fn(id: u32, page: u32, allowed_langs: SmallVec<[String; 3]>) -> Fut,
+    user_langs_cache: Cache<UserId, SmallVec<[String; 3]>>,
 ) -> crate::bots::BotHandlerInternal
 where
     T: Format + Clone + Debug,
diff --git a/src/bots/approved_bot/modules/download.rs b/src/bots/approved_bot/modules/download.rs
index 337c3c8..f3e2bc1 100644
--- a/src/bots/approved_bot/modules/download.rs
+++ b/src/bots/approved_bot/modules/download.rs
@@ -438,7 +438,7 @@ async fn download_archive(
         object_id: id,
         object_type: task_type,
         file_format: file_type,
-        allowed_langs
+        allowed_langs: allowed_langs.into_vec(),
     }).await;
 
     let mut task = match task {
diff --git a/src/bots/approved_bot/modules/random.rs b/src/bots/approved_bot/modules/random.rs
index eccf2a4..d808314 100644
--- a/src/bots/approved_bot/modules/random.rs
+++ b/src/bots/approved_bot/modules/random.rs
@@ -1,4 +1,5 @@
 use moka::future::Cache;
+use smallvec::SmallVec;
 use strum_macros::{Display, EnumIter};
 use teloxide::{
     prelude::*,
@@ -168,8 +169,8 @@ where
 async fn get_random_item_handler<T, Fut>(
     cq: CallbackQuery,
     bot: CacheMe<Throttle<Bot>>,
-    item_getter: fn(allowed_langs: Vec<String>) -> Fut,
-    user_langs_cache: Cache<UserId, Vec<String>>,
+    item_getter: fn(allowed_langs: SmallVec<[String; 3]>) -> Fut,
+    user_langs_cache: Cache<UserId, SmallVec<[String; 3]>>,
 ) -> BotHandlerInternal
 where
     T: Format,
@@ -293,7 +294,7 @@ async fn get_random_book_by_genre(
     cq: CallbackQuery,
     bot: CacheMe<Throttle<Bot>>,
     genre_id: u32,
-    user_langs_cache: Cache<UserId, Vec<String>>,
+    user_langs_cache: Cache<UserId, SmallVec<[String; 3]>>,
 ) -> BotHandlerInternal {
     let allowed_langs = get_user_or_default_lang_codes(cq.from.id, user_langs_cache).await;
 
diff --git a/src/bots/approved_bot/modules/search.rs b/src/bots/approved_bot/modules/search.rs
index e5e8b0e..9d873cc 100644
--- a/src/bots/approved_bot/modules/search.rs
+++ b/src/bots/approved_bot/modules/search.rs
@@ -3,6 +3,7 @@ use std::str::FromStr;
 
 use moka::future::Cache;
 use regex::Regex;
+use smallvec::SmallVec;
 use strum_macros::EnumIter;
 use teloxide::{
     prelude::*,
@@ -111,8 +112,8 @@ async fn generic_search_pagination_handler<T, P, Fut>(
     cq: CallbackQuery,
     bot: CacheMe<Throttle<Bot>>,
     search_data: SearchCallbackData,
-    items_getter: fn(query: String, page: u32, allowed_langs: Vec<String>) -> Fut,
-    user_langs_cache: Cache<UserId, Vec<String>>,
+    items_getter: fn(query: String, page: u32, allowed_langs: SmallVec<[String; 3]>) -> Fut,
+    user_langs_cache: Cache<UserId, SmallVec<[String; 3]>>,
 ) -> BotHandlerInternal
 where
     T: Format + Clone + Debug,
diff --git a/src/bots/approved_bot/modules/settings.rs b/src/bots/approved_bot/modules/settings.rs
index 31d5eb1..2cebe5c 100644
--- a/src/bots/approved_bot/modules/settings.rs
+++ b/src/bots/approved_bot/modules/settings.rs
@@ -12,6 +12,7 @@ use crate::{bots::{
 
 use moka::future::Cache;
 use regex::Regex;
+use smallvec::SmallVec;
 use teloxide::{
     prelude::*,
     types::{InlineKeyboardButton, InlineKeyboardMarkup, Me},
@@ -119,7 +120,7 @@ async fn settings_callback_handler(
     bot: CacheMe<Throttle<Bot>>,
     callback_data: SettingsCallbackData,
     me: Me,
-    user_langs_cache: Cache<UserId, Vec<String>>,
+    user_langs_cache: Cache<UserId, SmallVec<[String; 3]>>,
 ) -> BotHandlerInternal {
     let message = match cq.message {
         Some(v) => v,
diff --git a/src/bots/approved_bot/services/book_library/mod.rs b/src/bots/approved_bot/services/book_library/mod.rs
index 026f16a..fb6c2f0 100644
--- a/src/bots/approved_bot/services/book_library/mod.rs
+++ b/src/bots/approved_bot/services/book_library/mod.rs
@@ -2,12 +2,13 @@ pub mod formaters;
 pub mod types;
 
 use serde::de::DeserializeOwned;
+use smallvec::SmallVec;
 
 use crate::config;
 
 use self::types::Empty;
 
-fn get_allowed_langs_params(allowed_langs: Vec<String>) -> Vec<(&'static str, String)> {
+fn get_allowed_langs_params(allowed_langs: SmallVec<[String; 3]>) -> Vec<(&'static str, String)> {
     allowed_langs
         .into_iter()
         .map(|lang| ("allowed_langs", lang))
@@ -45,7 +46,7 @@ pub async fn get_book(
 }
 
 pub async fn get_random_book_by_genre(
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
     genre: Option<u32>,
 ) -> Result<types::Book, Box<dyn std::error::Error + Send + Sync>> {
     let mut params: Vec<(&str, String)> = get_allowed_langs_params(allowed_langs);
@@ -58,13 +59,13 @@ pub async fn get_random_book_by_genre(
 }
 
 pub async fn get_random_book(
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Book, Box<dyn std::error::Error + Send + Sync>> {
     get_random_book_by_genre(allowed_langs, None).await
 }
 
 pub async fn get_random_author(
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Author, Box<dyn std::error::Error + Send + Sync>> {
     let params: Vec<(&str, String)> = get_allowed_langs_params(allowed_langs);
 
@@ -72,7 +73,7 @@ pub async fn get_random_author(
 }
 
 pub async fn get_random_sequence(
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Sequence, Box<dyn std::error::Error + Send + Sync>> {
     let params = get_allowed_langs_params(allowed_langs);
 
@@ -96,7 +97,7 @@ const PAGE_SIZE: &str = "5";
 pub async fn search_book(
     query: String,
     page: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Page<types::SearchBook, Empty>, Box<dyn std::error::Error + Send + Sync>> {
     let mut params = get_allowed_langs_params(allowed_langs);
 
@@ -109,7 +110,7 @@ pub async fn search_book(
 pub async fn search_author(
     query: String,
     page: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Page<types::Author, Empty>, Box<dyn std::error::Error + Send + Sync>> {
     let mut params = get_allowed_langs_params(allowed_langs);
 
@@ -122,7 +123,7 @@ pub async fn search_author(
 pub async fn search_sequence(
     query: String,
     page: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Page<types::Sequence, Empty>, Box<dyn std::error::Error + Send + Sync>> {
     let mut params = get_allowed_langs_params(allowed_langs);
 
@@ -135,7 +136,7 @@ pub async fn search_sequence(
 pub async fn search_translator(
     query: String,
     page: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Page<types::Translator, Empty>, Box<dyn std::error::Error + Send + Sync>> {
     let mut params = get_allowed_langs_params(allowed_langs);
 
@@ -164,7 +165,7 @@ pub async fn get_author_annotation(
 pub async fn get_author_books(
     id: u32,
     page: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Page<types::AuthorBook, types::BookAuthor>, Box<dyn std::error::Error + Send + Sync>> {
     let mut params = get_allowed_langs_params(allowed_langs);
 
@@ -177,7 +178,7 @@ pub async fn get_author_books(
 pub async fn get_translator_books(
     id: u32,
     page: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Page<types::TranslatorBook, types::BookTranslator>, Box<dyn std::error::Error + Send + Sync>> {
     let mut params = get_allowed_langs_params(allowed_langs);
 
@@ -190,7 +191,7 @@ pub async fn get_translator_books(
 pub async fn get_sequence_books(
     id: u32,
     page: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<types::Page<types::SequenceBook, types::Sequence>, Box<dyn std::error::Error + Send + Sync>> {
     let mut params = get_allowed_langs_params(allowed_langs);
 
@@ -218,7 +219,7 @@ pub async fn get_uploaded_books(
 
 pub async fn get_author_books_available_types(
     id: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<Vec<String>, Box<dyn std::error::Error + Send + Sync>> {
     let params = get_allowed_langs_params(allowed_langs);
 
@@ -227,7 +228,7 @@ pub async fn get_author_books_available_types(
 
 pub async fn get_translator_books_available_types(
     id: u32,
-    allowed_langs: Vec<String>,
+    allowed_langs: SmallVec<[String; 3]>,
 ) -> Result<Vec<String>, Box<dyn std::error::Error + Send + Sync>> {
     let params = get_allowed_langs_params(allowed_langs);
 
@@ -236,7 +237,7 @@ pub async fn get_translator_books_available_types(
 
 pub async fn get_sequence_books_available_types(
     id: u32,
-    allowed_langs: Vec<String>
+    allowed_langs: SmallVec<[String; 3]>
 ) -> Result<Vec<String>, Box<dyn std::error::Error + Send + Sync>> {
     let params = get_allowed_langs_params(allowed_langs);
 
diff --git a/src/bots/approved_bot/services/user_settings/mod.rs b/src/bots/approved_bot/services/user_settings/mod.rs
index 40d4d25..562abce 100644
--- a/src/bots/approved_bot/services/user_settings/mod.rs
+++ b/src/bots/approved_bot/services/user_settings/mod.rs
@@ -1,6 +1,7 @@
 use moka::future::Cache;
 use serde::Deserialize;
 use serde_json::json;
+use smallvec::{SmallVec, smallvec};
 use teloxide::{types::{UserId, ChatId}};
 
 use crate::config;
@@ -41,17 +42,17 @@ pub async fn get_user_settings(
 
 pub async fn get_user_or_default_lang_codes(
     user_id: UserId,
-    cache: Cache<UserId, Vec<String>>
-) -> Vec<String> {
+    cache: Cache<UserId, SmallVec<[String; 3]>>
+) -> SmallVec<[String; 3]> {
     if let Some(cached_langs) = cache.get(&user_id) {
         return cached_langs;
     }
 
-    let default_lang_codes = vec![String::from("ru"), String::from("be"), String::from("uk")];
+    let default_lang_codes = smallvec![String::from("ru"), String::from("be"), String::from("uk")];
 
     match get_user_settings(user_id).await {
         Ok(v) => {
-            let langs: Vec<String> = v.allowed_langs.into_iter().map(|lang| lang.code).collect();
+            let langs: SmallVec<[String; 3]> = v.allowed_langs.into_iter().map(|lang| lang.code).collect();
             cache.insert(user_id, langs.clone()).await;
             langs
         },
@@ -65,8 +66,8 @@ pub async fn create_or_update_user_settings(
     first_name: String,
     username: String,
     source: String,
-    allowed_langs: Vec<String>,
-    cache: Cache<UserId, Vec<String>>
+    allowed_langs: SmallVec<[String; 3]>,
+    cache: Cache<UserId, SmallVec<[String; 3]>>
 ) -> Result<UserSettings, Box<dyn std::error::Error + Send + Sync>> {
     cache.invalidate(&user_id).await;
 
@@ -76,7 +77,7 @@ pub async fn create_or_update_user_settings(
         "first_name": first_name,
         "username": username,
         "source": source,
-        "allowed_langs": allowed_langs
+        "allowed_langs": allowed_langs.into_vec()
     });
 
     let response = reqwest::Client::new()
diff --git a/src/bots_manager/mod.rs b/src/bots_manager/mod.rs
index d04ed40..559060d 100644
--- a/src/bots_manager/mod.rs
+++ b/src/bots_manager/mod.rs
@@ -6,6 +6,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::Arc;
 
 use axum::Router;
+use smallvec::SmallVec;
 use teloxide::adaptors::throttle::Limits;
 use teloxide::types::BotCommand;
 use tokio::time::{sleep, Duration};
@@ -25,7 +26,7 @@ use crate::config;
 #[derive(Clone)]
 pub struct AppState {
     pub user_activity_cache: Cache<UserId, ()>,
-    pub user_langs_cache: Cache<UserId, Vec<String>>,
+    pub user_langs_cache: Cache<UserId, SmallVec<[String; 3]>>,
     pub chat_donation_notifications_cache: Cache<ChatId, ()>,
 }