Hello,
please, use just english in these forums. (or Czech which is not welcome, but tolerated)
1. if you have so many items, consider creating number of items stored in cache (that will reduce number of SQL queries)
2. if I calculate correctly, if you have 1500 products, in 3 languages, that could create about 3x 1500 URLs for products + another 2x 1500 URLs for "product question" page if you are using it. That is about 9000 URLs. So, together with categories and some other pages oyu might have, you could have ~10k URLs.
You have almost 4x as much, so it would be worth investigating a bit, what the other URLs are. (these may be invalid URLs generated by incorrect links in templates, etc.)
You will see these in URL Management and you can use different filters to reduce the number of the links. You can also post some examples here, so we may give you some hints.
Anyway, also consider the capacity and configuration of your server. At this site -
www.artio.net, we have about 60000 URLs stored at the moment and I think it runs quite ok, and it is far not the only site running on the server. So with dedicated harware, I would not really expect any problems with ~40k of records in table.
Also please mention what VirtueMart extension you are using.