Safari add-ons can cause performance issues or other situations

Third parties, such as shareware writers or software vendors, offer plug-ins or "add-ons" that add features to Safari or change its appearance. These files are usually installed in one of several locations such as the Internet Plug-ins folder, which is located in the Library folder inside your Home folder.

Here's the list of likely locations:

• /Library/Application Support/SIMBL/
• /Library/InputManagers/
• ~/Library/Contextual Menu Items/
• ~/Library/Internet Plug-Ins/
• ~/Library/InputManagers/

Note that the first two locations listed are in the root-level Library on your hard disk, not the user-level Library in your Home folder. The tilde (~) represents your Home folder.

If you use third-party Safari add-ons, you may run into a variety of issues. Some of them include:

• Safari runs more slowly than in its original state.
• You're unable to download files.
• Safari unexpectedly quits.
• You encounter other strange behaviors.

To resolve the issues, try removing anything you've added to the Internet Plug-ins folder or the SIMBL folder, and then relaunch Safari. If this fixes the issue you were having, check the website of the add-on's developer to see if there is an updated version.

Additionally, you may want to review a couple other pertinent articles that discuss Mike Solomon's PithHelmet and general Safari troubleshooting.