Cache and speeding up my comp.

No, caches exist to improve performance. A good general rule to follow is if you don't know what a file/folder is used for, don't delete it. This is especially true in System or Library folders.

The most effective method for complete app removal is manual deletion:

Best way to FULLY DELETE a program​

Macs are not immune to malware, but no true viruses exist in the wild that can run on Mac OS X, and there never have been any since it was released over 10 years ago. The only malware in the wild that can affect Mac OS X is a handful of trojans, which can be easily avoided by practicing safe computing (see below). Also, Mac OS X Snow Leopard and Lion have anti-malware protection built in, further reducing the need for 3rd party antivirus apps.

Mac Virus/Malware FAQ​

1. Make sure your built-in Mac firewall is enabled in System Preferences > Security > Firewall
   
   
2. Uncheck "Open "safe" files after downloading" in Safari > Preferences > General
   
   
3. Disable Java in your browser (Safari, Chrome, Firefox). This will protect you from malware that exploits Java in your browser, including the recent Flashback trojan. Leave Java disabled until you visit a trusted site that requires it, then re-enable only for the duration of your visit to that site. (This is not to be confused with JavaScript, which you should leave enabled.)
   
   
4. Change your DNS servers to OpenDNS servers by reading this.
   
   
5. Be careful to only install software from trusted, reputable sites. Never install pirated software. If you're not sure about an app, ask in this forum before installing.
   
   
6. Never let someone else have access to install anything on your Mac.
   
   
7. Don't open files that you receive from unknown or untrusted sources.
   
   
8. For added security, make sure all network, email, financial and other important passwords are long and complex, including upper and lower case letters, numbers and special characters.
   
   
9. Always keep your Mac and application software updated. Use Software Update for your Mac software. For other software, it's safer to get updates from the developer's site or from the menu item "Check for updates", rather than installing from any notification window that pops up while you're surfing the web.

That's all you need to do to keep your Mac completely free of any Mac OS X malware that has ever been released into the wild. You don't need any 3rd party software to keep your Mac secure.

You don't need to worry about "useless" data, unless it's useless user files you've created. Having files stored on your computer have no effect on its performance. If it's more disk space you want, you'll get much more impact by moving user files to an external drive than you will by messing with system files. If it's better performance you're looking for, this may help:

Performance Tips For Mac OS X