The best I could suggest is more debug symbols or something, I'll work with my friend to figure out the deep debugging (gdb-type stuff) as well, since if we could even figure out the offending allocation, that would probably give us some insight!
The large memory allocation could be in part due to wine, but I'd be surprised if it were over 500 MB, and even that number is probably too high for what wine's injecting (A lot of it is handled by "wineserver", which is a seperate process and therefore not in this number)
for some informal numbers, I'm getting 9 or 10 fps in the first benchmark when things are mostly in view, and 5-9 fps in the second (measured using mangohud).
I managed to get the game running with wine-ge 8.13, which yielded the following results:
508/20.3/7.6
331/13.2/4.7
286/11.4/2.4
I would like to state my graphics system is a bit of a mess from switching drivers a few times and not really being bothered to do it properly, so a bit of a caveat to that!