Why did many old games run like crap on my old PC?

I'm about to upgrade, but I was wondering why so many games ran like crap on my old PC when even recommended requirements appeared to be met. Maybe this will help me understand hardware a little better too.

My old PC specs are:

Windows XP

Intel Celeron 2.60Ghz

Radeon HD 3450 512MB

2GB RAM

Many games ran well, but here are a few examples that didn't. Low settings were recommended settings for games like Battlefield 2. And yet looking at requirements, it even looked like it met recommended. Did I miss something? Counter-Strike Source became unplayable when there were more than 5 bots. Also, Command&Conquer 3 got slow pretty fast. Need for Speed Carbon was a bit slow. A game like Rainbow Six 3 was perfectly playable, but simply didn't have that top-class framerate. Unreal Tournament 2004 was also perfectly playable, but became laggy when the amount of bots was close to max. Red Orchestra 1 was pretty slow and a game like Vampire - Bloodlines got slow in outside areas.

Could someone have a look at these games and tell me why my PC wasn't able to run them perfectly? I'd like to understand this a bit more. It will also be interesting to try these games out on my new PC for comparison.

The problem is that Intel Celeron 2...... its a single core cpu and its a bottom tier performing cpu, its does not met many of the those games recommended requirements

Many of the games that your running into performance issues with is because they require at least a fast single core or dual core cpu.

i have the same GPU in a 2007 sony laptop i have. Its terrible and it would chug any game i ran with it. Also the cpu is really weak also. Mine was an intel 2 core p8400... which was ok for the time, but not a gaming cpu. Same thing goes for you also, i can't see anything running on that pc well.

Im not sure what res you run at, but my laptop was 1080p and that radeon HD 3450 video card was far too weak for a 1080p resolution.

The requirements they put on games are very hard to get a read on how they will work. Some are well optimized and actually do run on what they say, but others will run terrible even if you have the newest cpu and gpu you can buy.

Also, a celeron is the cheapest form of intel cpu you can get. Not meant for gaming of any kind. I had a celeron 500mhz back in 1999 and was actually good for games but things have changed.