You could try to disable NCQ by parameter before booting, as it seems to be some compatibility issue that makes the kernel to disable "queued TRIM support", as reported via Dmesg at:

[ 2.344002] ata1.00: disabling queued TRIM support"

Check this bug https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1591293 It seems that it takes many seconds to the kernel to decide to disable NCQ.