My N900 is also laggy, when I just cant stand it I reboot it and I do this on daily basis. What I hate most is when you have an incoming call, ringtone rings but answer button has not appeared yet. Sometimes it wont appear at all and Iam just unable to pick up the call. But its still a best phone I ever had and I wont be switching it untill N9 shows up.

Why would he want to get a a 3310? You're just being flippant and quite ridiculous. He wasn't dissing the N900, just making an observation that it's slower with every subsequent Software Update.

I've been told the main issue is the tiny size of the RAM, and based on the way performance increased on my desktop machines when i've increased the RAM on them, that explanation sounds very plausible.

when im doing software updates or anything with app manager, everything is ok presuming im not multitasking... if i get a text or email or something else, BAM unresponsive for like 5 mins.
besides from that i reckon everything is fine im oced to 900mhz

nope i think if it was any more instant opening the keyboard it would have to be psychic and actually unlock slightly before! i have oc'd to 1ghz though and i avoid using desktop widgets etc that i feel slow it down. the only time i notice lag is during the auto update check (its really crippling, i can tell soon as it starts) or playing games when i recieve an email etc it will slow a little.
if you dont want to oc try swappolube or some of the other performance tweaks floating around here.

optimize n900 script on a beecon is a lifesaver