Either your RM2 has something wrong with it, or you're (enviously) sensitive to latency. Both the marketing team[1] and independent testing[2] show that latency is under 25 ms.
That also doesn't seem consistent with GP post that "the input lags when I use the pen is so much that it distracts me while writing a sentence" which shouldn't be in the same category as 25ms.
I have an iPad Pro, daylight and remarkable 2. iPad Pro is definitely the fastest. The daylight and rm2 are slightly slower and I do notice it, but they are definitely fast enough. The RM2 is the slowest and that is just e-ink physics at that point. I was pleasantly surprised by the speed of the daylight when I used it.
It's all lost on me although, since I don't really like pen input. I find the RM2 frustratingly slow for an epub e-ink reader. Compared to a kindle or others it's weirdly slow, even when pen input is fast. The daylight solves the outdoor computing problem for me.
That also doesn't seem consistent with GP post that "the input lags when I use the pen is so much that it distracts me while writing a sentence" which shouldn't be in the same category as 25ms.
[1] https://support.remarkable.com/s/article/What-s-the-differen...
[2] https://youtube.com/watch?v=g34SVxTjGIA&t=3348s