Hello Kamil already gave you solution in FAQ link. Please go there and fallow the instructions. Please note that it is only your database configuration issue. This is not any bug (nor vBulletin nor vBET - sorry Kamil didn't make it clear).

On your server it happens only when vBET is on, because only then translations happens. If translation is not yet cached then it goes to Google. Google gives you results in long time (that is why we are caching it – to get it fast next time) and it appears that often whole request execution time is longer that your database connection time. So this is easy configuration issue which only requires to change your database connection time to longer. Please fallow instructions in FAQ for more details

If you need some more information please just write