and the windows qt wallet works fine but i think it use a bit to much memory (2.4gb) others good wallets use less than 1gb, bitcoin qt for example use less than 200mb
Firstly, that's a lie. Bitcoin doesn't use only 200MB.
Secondly, Bitcoin has only half a million blocks. DigiByte has over 9 million. You can see more about this here:
https://github.com/digibyte/digibyte/issues/144