Tvheadend

Not implemented in old version
update to 4.3.1000+

Yes, confirmed to work in 4.3 version but unfortunately, after some playing time I get log with errors:
"mpegts: too much queued table input data (over 2MB)..."
and that makes tvheadend web unresponsive and (almost every time) Kodi disconnect As I found, this is some old tvheadend error but I don't know why I didn't had it in version 4.2.8 and here it jumped out.. I tried all suggested that I managed to find, but I can't fix this error

Ok, looks like transcoding uses too much resources because tvheadend uses 150-190% processor when transcoding. As I can logically conclude, this leads to not clearing input buffer of data received from DVB-T resulting in "too much queued table input data...". All together, looks like my setup can't work Here I would kindly ask for any idea but first, I'll explain why I wanted to do setup transcoding at first place.
I have an IBM X3200 M3 server (8Gb RAM) with OpenSuse and two USB DVB-T devices running tvheadend. Also, I have two RaspberryPi 3 B+ connecting to the server. DVB-T signal is h265, 1080p (national television in Croatia). This was all working ok with little RPi overclocking, well, until a couple of days back: image when watching TV sometimes is twitching (when a lot of things change in the frame). I was thinking to transcode h265 to h264 and send that signal to RPi but that ended as described just above. So, what would be the best way to solve this problem?
Options:
1. Replace Raspberry Pi 3 with Raspberry Pi 4 (will Pi with 1Gb RAM be OK because ore other variants are unavailable for now)?
2. Buy an GeForce and install it to the server?
3. some other idea...

Thanks