I very intensively use an SSD, but never fill the filesystem more than 60%.
Will the performance and endurance of the SSD increase in case with bigger Over Provisioning space ? The storage controller does not support TRIM, so there is only internal garbage collection possible.
No, you won't see any benefit to endurance or performance from larger amounts of over provisioning ( more than 10-20% ). Note though, that over provisioning does not mean simply keeping free space within the filesystem, since adding and removing files over time will tend to write to different parts of the disk. You have to actually leave part of the disk unpartitioned so that it is never written to.
Anandtech has a write-up on the performance of over-provisioned drives from a few different vendors. While 50% did show slight improvements over 50%, 25% resulted in similar performance and was the recommended amount to use.