Macbook Pro periodically slow/beachball
This is a 2011 highend 15" MBP that should run quite nicely. But it doesn't. Tried everything I can find, no answer so far. Looking for ideas before it gets tossed. Thanks in advance.
Model: Macbook Pro 15", late 2011, 2.2G i7, 8G ram
(MacbookPro8,2, Boot ROM ver: 87.0.0.0, SMC ver: 1.69f3)
Its like new, so it would be nice to get it working properly. My daughter was using it till she got a new Macbook recently. Its been slow for a few years. She thinks it happened after an update awhile back.
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Symptoms
Login screen takes almost 1m to come up. Once password is entered it takes another minute of beachball to be logged in.
Once logged in, periodically the beachball comes up or is otherwise unresponsive for 10s of seconds then its fine for a bit. Always low CPU usage in the activity monitor (unless running something known to be CPU intensive)
Tried turning on Guest on a whim. This is where its gets interesting. Click the Guest checkbox and it takes at least 1-2m before the box is checked. Same unclicking. CPU usage remains low BUT the preferences process turns red during the wait.
All the symptoms seem to indicate processes are waiting for "something" (that is not CPU dependent).
For comparison my wife's Base 2012 13" MacbookPro turns the Guest flag on/off immediately. It also runs an external screen while using zoom etc for online classes and it has NO performance issues. And I also have an old 2008 base Samsung laptop than runs Windows _with_ Virtualbox with little performance lag. So this topline 2011 MBP _should_ have no performance issues relatively speaking.
Other than the periodic severe slowness, it runs fine ... plays videos, runs apps, boots, etc all good.
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Tried:
Complete re-install of Mac OS on new SSD. No data/apps were carried over, just a clean install. No change. (High Sierra, 10.13.6)
Short and long hardware diagnostics ... all good, no errors.
Swapped RAM, no change (8G RAM)
Dis-connected the battery, DVD player, anything I could unplug, no change.
PRAM/NVRAM/SMC reset, no diff.
Replaced the HD cable, no diff.
Installed Windows and Linux. Similar symptoms. Just periodically slows, you can move the mouse, sometimes you can move a window but otherwise unresponsive for 10s of seconds. CPU usage remains low.
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Have not tried:
Have not re-flashed the firmware. High Sierra errored out on trying to run the re-flash program ... app too old as I recall. And I don't have Lion 10.7 DVD's and can't download the ISO from Apple to try re-flashing.
Have not tried another main battery.
Have not replaced the PRAM battery (which as far as I can determine it no longer has anyway, or is integrated into the main battery.)
Other than the HD, HD cable and RAM no other hardware has been replaced.
MacBook Pro 15″, macOS 10.13