MacBook Pro instability over the last few months
i hate this beachball, but you can do some things, first is to start with cmd+r and go to terminal and write     csrutil disable and reboot. now your sip is disabled and you should  enable it in the same way when your finished with this steps:   


Go to About this    mac under the apple in the upper left and click
on More info
Click on system report
make a note of what it says after Model Identifier


go to your masterdrive–System-Library–Extensions–
IOPlatformPluginFamily.kext-Contents–Plugins–ACPI_SMC_PlatformPlugin.kext–
Contents–Resources – find the name from step 3 and move it to a
folder that you can find again if needed.



Now reboot and check, if your mac is running better. you can also    check in disk utility the kerneltask before and after youremoved the    file. dont forget to enable your sip now. 
what is about your cpu    temperatur or fan, to high? you can solve this
only by disconnect you    battery and powersupply. Now hold down the
on/off button for min 5    better 10 seconds. Rebuild your batterie
and reboot. Next thing is pr    ram reset, start while holding
cmd+option+p+r, wait until you hear    the loud mac startup sound
and release then the mac start up again.    clear cache by start
while holding shift, log in and reboot.  that    should make a hugh
    difference like before. you can run from time to    time in terminal
    sudo purge   to clear your used ram. cheers**