To swerve a bit off-topic, the original Celeron processor was a piece of crap, and existed in the speeds 266MHz and 300MHz. It was basically a Pentium II without the L2 cache and in socket, and not slot form, making it much cheaper to produce. The Celeron A, on the other hand, was released in the speeds 300MHz up to 450MHz, was much better, including 128kb of on-die L2 cache (The Pentium 2 had 512kb of off-die cache running at half the clock-speed) running at full speed, making it actually faster, clock-to-clock, than a Pentium 2 of the same clock speed. Not to mention a whole lot cheaper.
The whole problem with the Celerons is the bad name they have due to the original, crappy ones. 400MHz Celeries are, on the other hand, of the Celeron A flavor, making them just fine, so I don't wanna hear anyone dissing Celerons.
As for the memory usage, yes, it's horrible, but most of it is used in model loading, meaning it's just some more disk-thrashing when you're loading. It's still bad, and an effort will be made to cut memory usage down.