Help: I upped the RAM, but Computer is still sluggish

Question

Hello,
I increased the memory of my Powerbook G4 (12 inch, 1 GHz). The original RAM was 256MB and I added another slot of 1G -- brings the current total to 1.256 G.
The computer is still sluggish, though. Multi-tasking is slow. It "thinks" alot and "spins" a lot. Tick, tock, tick, tock.
I've been watching the memory info on the Activity Monitor for the last few weeks/months. I've noticed that after I close down some applications, it doesn't seem to free up the memory. For example, right now it shows:
Wired: 120.19 MB
Active: 342.08 MB
Inactive: 791.89 MB
TOTAL USED: 1.23 GB
TOTAL FREE: 24.89 MB
VM size: 4.96 GB
Page ins/outs: 39153/1372
Why does the computer not free up all that Inactive memory? Rebooting the computer only fixes the problem for a moment.
Is there a configuration setting I've missed somewhere?
Please help! Thank you!!!
Powerbook G4   Mac OS X (10.4.7)  

Answer 1

WorldTraveller,
As a computer tech I'll try and explain the basics of memory usage in OS X. It works differently to say Windows if you come from PCs.
Wired: Used for vital system files of Mac OS X, that has to be in RAM all the time.
Active: It is memory that is actively in use within a certain time period.
Inactive: Is either: a) memory that is being used by applications you have open but it hasn't been used in a while or b) memory that has been used by a previously opened application. When more memory is required by a program this is the area that typically gets shuffled around first.
Free: Unused memory that can be used by new applications. The system will always keep some free memory around so it's available promptly if a program requests it.
You can think of inactive as a cache. If you have say Safari open then you close it & restart it, then it will open up faster the second time because it'll still be held in inactive memory. Or a holding area for apps running in the background not being used. This why inactive has the highest number usually. Overall I wouldn't worry about the numbers much coming from the PC field for 18 years, OS X memory management is far more effective then Windows.
As for the hard drive: I noticed my 1.33 Ghz model the fan did run and come on far more then my original 867 Mhz model. One of the reasons I really missed my Rev A running Jaguar the fan rarely came on. In the end I put it down to more heat being generated from the faster chip and Apple did change the level at which the fan kicks in after Jaguar. Mainly because I think most complained about the heat. Personally I'd have taken slightly more warmth for silence. As long as the fan doesn't stay on then it's normal from my experience. I must say my new mini is as quite as my original PB so I can't complain. Until the super drive kicks into high gear then it sounds like a fighter jet LOL.
Anyway I hope this has helped explain things a little better.
Rick
1.66GHz Intel Mini Duo, 1GB RAM, 100GB HD   Mac OS X (10.4.7)