REW/FFW work fine for me. I can use 2x, 4x and 8x speeds without issue, but 16x and higher give odd pauses while cuing through file. I've never really worried about it, because I always felt it was a filesize issue. (My main TV downstairs is wirelessly connected over 802.11ac, but my TV streams are MPEG2, and while the average program is about 8-10Mbps, the bitrates at times can go up to 20Mbps.)
I have found I much prefer using the right and left arrow keys to seek in a recording. By default Kodi sets these steps as: 10s, 30s, 1m, 3m, 5m, 10m. So each time you press the arrow key, it will advance to a specific point in time. Seeking this way is much faster, so I use this almost exclusively.
