Computers do not run software fine one day and not fine the next unless there has been a change.
Unless your harddisk is VERY VERY OLD (DMA66 or older) it should have a fast enough interface for the data transfers LFS requires. If you have a hard disk this old I would assume the rest of your system is this old and THAT will be the cause of your issues.
Unless a modern HD is damaged and about to die or VERY full IT WILL NOT CAUSE PROBLEMS. Hard disks work or do not, there is no in between state unless they are about to transition from one state to the other.
What version did you come from to move to X2. Did X work well for you?
Both should post your system specs, loads of things can cause judder but a hard disk should not be one of them. A slow CPU, not enough ram, crap GFX card or combinations of the 3 will cause it.