Is there a way to slow down an SSD trim so it doesn't affect the drive's read performance while it is in progress?

On my test Linux box with a Transcend TS2TMTE662T2-G1 SSD installed. I created a 100GB dummy file on my 1.8TB ext4 partition, and then I ran cat <bigdummy.bin >/dev/null to sequentially read the data from that file as quickly as possible.

With cat running, I ran iostat -t nvme0n1p6 --human 1 in a different shell window to monitor what the SSD's read-performance was like... it looks pretty good, I'm reading in ~2.2 gigabytes per second:

Device             tps    kB_read/s    kB_wrtn/s    kB_dscd/s    kB_read    kB_wrtn    kB_dscd
nvme0n1p6     18232.00         2.2G         0.0k         0.0k       2.2G       0.0k       0.0k

I then used rm to delete about 600GB of (unrelated) files from the partition, and then I ran fstrim --all to tell the SSD to start erasing the newly-discarded blocks. While that trimming was going on, I looked at iostat's output again to see how my cat process's read-performance was now faring:

Device             tps    kB_read/s    kB_wrtn/s    kB_dscd/s    kB_read    kB_wrtn    kB_dscd
nvme0n1p6       215.00        18.1M         0.0k         8.8G      18.1M       0.0k       8.8G

Ecch, not very good at all. Read bandwidth has been reduced to a measly 18MB/sec, and the transactions-per-second is similarly down by a factor of 100.

It's probably unreasonable for me to expect 100% of normal read performance from an SSD that is also in the middle of doing 8.8G/s of kb_dscd's... but since the block-discarding operation isn't particularly time-critical (in that I don't care that much whether it completes in 30 seconds or continues for 30 minutes), is there any way for me to slow that process down so that my drive's read-performance won't be so badly impacted while it is going on? e.g. if the SSD was only doing 500 M/s of kb_dscd operations, it would (perhaps) have more time left over to handle its normal read-I/O tasks at something approaching its usual rate?

(motivation: this is for a media streaming box that will eventually want to do simultaneous recording and playback, potentially 24/7, and it would be really nice if I could periodically initiate TRIM operations without significantly impacting the box's ability to continue streaming content at the same time.)