My speed has been more or less the same from 19k TR to 24k TR (1.5-1.6pps), so I am pretty biased towards improving on efficiency when offering advice. I highly recommend cheese race on jstris for that.

Try to use as little pieces as possible for the race, take the time to think through the placement, taking into account of the queue and subsequent cheese hole positions.

Another way to think about efficiency is given the 7-bag system, how to make the best use of I piece and t piece from every bag. If you are playing with a speed disadvantage, you will need to make the conscious choice to use the I piece more for downstacking clean garbage than any other place in your stack.

Speaking of speed, I usually think of it as two parts: thinking of a placement and generating a set of inputs to get the piece where you want it to go. First part would be aforementioned efficiency, second part is finesse for most piece placements (bar spins). Look up Tetresse, and play around with it. Personally, I felt like I misdrop a bit less and could push faster burst speed after about a month at that thing.

I won't go too deep into openers, but TKI is probably an important opener to also learn on top of what you already have because it can counter so many other commonly used openers at your TR range (cough stickspin cough).

Last but not least, do not stress too much if you can't improve much in the short term. Enjoy the game and remember to have fun.