Network related issues.You need to determine if it’s the network solely that’s to blame or is part of the problem. So disconnect from the network and attempt to like tasks offline to determine if the problem is computer or network related, this it might be both even. Take the machine to another network, cheap use other computers on the same network etc., in the process of elimination. Consider if the router is old, the Internet connection speed isn’t adequate, you have leechers, bad cables, electronic interference or too many Wifi’s in the area fighting over channels. The purpose of this User Tip is to focus on computer issues, if the problem only occurs while you are online, then see this User Tip of possible WiFi/Internet related issues if or before you have eliminated the computer as the source of the slowdown.
Too many programs running.Look in the Activity Monitor, click on CPU and “All Processes” and attempt to gauge if you have to many programs running that’s taking all of your available RAM and thus “swapping” memory with the slower boot drive. Programs have memory requirements, too many at once will over load your RAM and slow down your machine, and in 10.7 slow down your boot time. Check the log in items in 10.6 too in your System Preferences > Accounts. For a runaway process, sort by CPU % and see what’s taking up a lot and attempt to force quit it or reboot the machine, check for updates, it might be a bug that got fixed.
Server / Hardware is obsolete. Make sure your hardware is beyond the minimal requirements of the operating system version hardware requirements. This tends to also to apply to a lot of software, minimal specifications outlined by the software maker are usually below par.
Slow internet connection. No matter how fast your Internet connection is, there are times when things will slow down. Some ISP’s are testing IPv6 and may cause issues, turn it off in your System Preferences > Network > Advanced > TCP / IP. Sometimes it’s not your fault, it’s the ISP having troubles, a loose connection, etc.