[xwiki-users] memory usage

Hi all, I tried to put a big file in my wiki (200Mo). Because of the size, I truncated it in 8 pieces. When I uploaded the fourth one, the wiki kinda crashed. So I stopped it and restarted it but I always get error 500. So I put more memory in the JVM (I was using 1300M and I put 1800M). And now it works. But I'm a bit scared with this memory consumption because I have something like 100Mo of file attachment and the server is quite full :/ Is it because I'm using HSQLDB? If yes, is it possible to migrate to something else? What's the best choice?