how do I speed up my old slow emac

1) Make sure you have at least 10-15% free hard disk space... (ie if you have 80GB hdd, keep at least 8GB free space)

2) Leave computer running (not sleeping) overnight, or download MacJanitor and run the maintenance scripts. Mac OS X runs these at about 2am if the computer is on... otherwise you can use 3rd party software to make them run (or also research how to do it using Terminal).

3) If using the latest browsers etc, consider downgrading. Modern web browsers are resource hungry, thus slower on old machines. (As a general piece of advice, this applies to everything in computing - you buy a computer in 2004, software evolves over 6 years and expects computing power from 2010... we upgrade the software without considering that the computer is much older than what the software was designed for... even though it might be "compatible")

4) Increase your RAM. Depending which eMac, you can go up to 2GB of RAM... the more the better.

5) Restart. If you only sleep your computer, instead of shutting down (which is fine to do), but you notice a slow-down... try restart. It refreshes the VRAM etc etc etc and could help the computer to clear its head of things that it's been worrying about unnecessarily.

Look at these links

Mac Tune-up: 34 Software Speedups
http://www.macworld.com/article/49489/2006/02/softwarespeed.html

52 Ways to Speed Up OS X
http://www.imafish.co.uk/articles/post/articles/130/52-ways-to-speed-up os-x/

Tuning Mac OS X Performance
http://www.thexlab.com/faqs/performance.html

11 Ways to Optimize Your Mac's Performance
http://lowendmac.com/eubanks/07/0312.html

The Top 7 Free Utilities To Maintain A Mac.
http://mac360.com/index.php/mac360/comments/thetop_7_free_utilities_to_maintain_amac/

Mac OS X: System maintenance
http://discussions.apple.com/thread.jspa?messageID=607640

 Cheers, Tom 😉

I get stuttering video,

The suggestions the others posted will likely help other slowness issues, but choppy web video plagues just about every G4 user any more. It's the way video technology has evolved--it is no longer optimized for older PPC processors. I've even heard a few G5 users say they are starting to have trouble with video.

Adding RAM with not help this specific area, but will in the others you mentioned. System Profiler (in your Utilities folder) will tell you what RAM you need. In Profiler's opening screen, the second line is "Machine Model" (in Tiger). If the code following that is "PowerMac4,4" you use PC133 RAM and your max capacity is 1G (2 x 512Mb modules); if "PowerMac6,4: you use PC2700 RAM and the max is 2GB RAM (2 x 1Gb modules.)

Once you get this code, it would be helpful if you place it in your profile as it will get you answeres faster if people don't have to ask which of the two major eMac variants you own.