Slow Mavericks and Activity Monitor Uselessness

Question

The recent Mavericks update may have improved performance to some degree, but I'm still experiencing unusual slowness of apps often.  One of the most irritating things is that the one app I except to help me shed light on the cause of the slowness, Activity Monitor, typically shows NO unusual heavy system load when I observe apps being slow.
For example, I click on + in Safari to create a new tab.  I expect immediate response, an immediate new tab being open.  Instead, it takes maybe 5 seconds, perhaps even 10 seconds.  So, I immediately switch to the Activity Monitor window to see if I can identify what might have caused the slowness.  I think that maybe the CPU become extremely overloaded during that brief period.  But I see nothing in Activity Monitor to clue me in as to what the problem was.
To me, this means Activity Monitor is not monitoring relevant activities.  I don't know why Safari is slow opening at tab, but whatever it is doing should be an activity that Activity Monitor monitors, since it obviously is something that takes the machine a lot of time to do.
Could a knowledgeable person in Apple's software department respond here and say something about why opening a new tab in Safari takes so long?
ted

Answer 1

Please read this whole message before doing anything.
This procedure is a test, not a solution. Don’t be disappointed when you find that nothing has changed after you complete it.
Step 1
The purpose of this step is to determine whether the problem is localized to your user account.
Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”
While logged in as Guest, you won’t have access to any of your personal files or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.
Test while logged in as Guest. Same problem?
After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.
*Note: If you’ve activated “Find My Mac” or FileVault, then you can’t enable the Guest account. The “Guest User” login created by “Find My Mac” is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.
Step 2
The purpose of this step is to determine whether the problem is caused by third-party system modifications that load automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Boot in safe mode and log in to the account with the problem. Note: If FileVault is enabled on some models, or if a firmware password is set, or if the boot volume is a software RAID, you can’t do this. Ask for further instructions.
Safe mode is much slower to boot and run than normal, with limited graphics performance, and some things won’t work at all, including sound output and Wi-Fi on certain models. The next normal boot may also be somewhat slow.
The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin.
Test while in safe mode. Same problem?
After testing, reboot as usual (i.e., not in safe mode) and verify that you still have the problem. Post the results of steps 1 and 2.