The game runs slow on +100 levels

[Eric]

The runs smooth and everything works fine, but when I enter the higher levels the game runs extremely slow. Even on the lowest settings or chaning my graphic driver to performance. As far as I see it happens when there are more ships. But if I play with the new character and there are the same amount ship it isn't slow down on max settings.

Could my saved file cause this? I use the very same ship since the Drox Operative version 1.020, and now I have the GOG 1.023 with IoTA.

Windows XP SP3
Pentium4 3 GHz
2,5 Gb RAM
NVidia GeForce 9400 GT, 512 Mb VRAM

Maybe I can try on my wife's laptop because that is stronger.