I read this in FAQ about GT Pro slow #7 (quoted below) and checked but all seems Ok
What we can do about making it work faster? Please advice what else we can try?
==Info from GT PRO FAQ==
7. The translated page is always slow.
- Make sure that gtranslate/cache/XX folders are writable. After visiting a translated page, you will be able to find files in the appropriate language folder. If you don't see them, then set gtranslate/cache/XX folders permissions to 777.