Hi!
I see this topic is kind of abandoned by now but I wanted to check in anyway.
I had a similar problem but I would argue that in my case that it was in fact RAM related. The issue seems to be that AoE2:DE currently consumes a lot of RAM until there is non left for some people. While waiting for a fix from the devs there are some temporary fixes you can look into if you find that it is in fact the RAM that you struggle with too. You can find more info about this issue and how to temporarily fix it on an older thread here: [Bug] Kotyan Khan Campaign mission 2 Crash
B.R. Fondis