Comment 29 for bug 1852001

I haven't verified if this actually fixes the problem but it seems to make a huge difference in 'free' memory as shown by 'free'.

I had already closed my VMs by the time I tried this so haven't verified if it stops the long freezes yet.

              total used free shared buff/cache available
Mem: 31030 5331 2790 5347 22907 19900
Swap: 32767 3130 29637

echo 3 > /proc/sys/vm/drop_caches

              total used free shared buff/cache available
Mem: 31030 5349 17122 5312 8557 19915
Swap: 32767 3130 29637

Notice the 2790 -> 17122 change above in 'free', and 22907 -> 8557 for buff/cache.

It appears the kernel doesn't get rid of cache in a reasonable timeframe at the expense of swapping programs out to disk while i/o is happening, which causes gui freezes.