I noticed that the guiding processing speed is a bit on the slow side. My exposure is set to 0.5 seconds and the delay is set to 0.0 seconds.
Nevertheless, corrections are only made every 3 seconds.
How can I speed up this process so that the guiding can intervene more quickly?
I also wonder why there is the option to remove the backlash after calibration with DEC, but this option does not exist for RA.
What is the explanation for that?
Backlash is not relevant for RA axis: during tracking and guiding, RA drive never reverses motion (it only slows down when correcting towards East), so any backlash, if present, can't produce any effect.
So am I understanding correctly by saying that the RA stepper runs continuously in one direction and only varies the speed, but never stops and/or reverses?
Yes: guiding speed is usually configurable in mount settings as a fraction of the tracking speed, defaulting to 0.5x. Assuming this default value, for example, guiding pulses towards east will slow down RA tracking to half speed, guiding pulses towards west will speed it up to 1.5 x tracking speed.
You could try reducing the aggressiveness of the RA corrections. You'll notice that RA is continually swapping direction. This is because its over-correcting and therefore has to go into reverse, giving you a saw-tooth graph.
Rather than doing more corrections you might get a better result doing fewer but better targeted corrections.