My server started crashing after I started removing mods. Help?

So earlier today my modded server started crashing after I removed mods as the server wasn't able to keep up with player movements and started rubberbanding. So then I removed some but then it suddenly began crashing. It keeps saying it ran out of memory or it took to long to start even though it worked before and it had more mods. I have checked the modlist constantly and all the support mods are there. Please help.