my friend has a pc that can run 3A games on ultra / 4k without any problem, but he gets 5fps on zvz. Its ok, thats normal, this game is badly programmed on the video usage and uses way too much of the videoboard.
4gb of ram is a non issue unless you have a pair of 15 year old DDR2 sticks running at 800mhz.
The main problem is how the game handles asset loading:
Every single texture, animation, effect is loaded "on the go", nothing is pre-loaded.
All those freezes while youre getting dismounted by 3 people is from your hard drive choking by suddenly receiving 10 requests for loading animations into the RAM.
Any sizeable clump of assets loading at the same time freezes the game with only high-end SSDs catching up to the pace.
Also asset unloading is handled poorly too, after running through BZ areas at a high pace your RAM will fill up very fast, and if you dont have any software to clean it up on the go you're due for a game restart.