Going EVA destabilizes framerate

[Somgosomgo]

Not sure where this belongs because it happens regardless of whether I have mods installed or not so I'll post it in this section.

I expected at least a few performance issues on my potato as with every KSP update. Today I noticed that whenever a Kerbal goes EVA, framerate drops from a (fairly) solid 30-25 (in space) to an extremely unstable state that varies between what looks like 5 and ~15, basically making everything barely playable for the remainder of the session. When two kerbals are out of the vessel simultaneously I don't get more than 10 fps. In addition to this, KSP seems to load slightly faster when I use the 32 bit version (when running 64 bit transition between all screens takes slightly longer and the main menu hangs up for a few seconds before becoming usable).

I run KSP on Windows 7 64 bit.

Edited April 23, 2016 by Somgosomgo