I also ran it on a netbook (some variant of a 901?) for a couple years, and it was great. I'm also pretty sure it would be less great now, even if I were running the same version.
People delete email?
I started using the gmail's "archive" button in ~2009 and now I see 112,315 conversations in the "all mail" section. That's probably 200k emails in total. The fact that web mail always runs at the same speed regardless of how much mail you have is seriously underappreciated.
(Some operations like creating a filter and applying it to all past conversations does take 5 seconds, but this doesn't block the UI so it's not a deal breaker)
What is the advantage of the archive, if you have to rely on search to find stuff anyway?
This lets you turn the inbox into a sort of TODO list that only shows you stuff that's still pending. Of course you also have to use filters aggressively if you wanna maintain inbox-zero without having to manually archive every "your bank statement is ready" email.