Switch to Dietpi for x86

Hello, i recently attempted to power down my aging x86 server for a new Pi4b. However i hit a snag. I am a heavy Plex user as Plex handles my cable and dvr. The pi4 plays everything fine except live tv from a HD Home Run Prime cable card tuner. I was told on the HDHR forums to upgrade to the newer HDHR that handles transcoding, decoding or whatever on the HDHR itself and not on the pi. However i don’t want to spend the money on new HDHR as mine works great on x86 using Plex. If i use DietPi for x86 do i need to adjust any caching to avoid my old usb 2.0 bus on the x86 system ? I have a single 4TB sata drive do i need to adjust anything in dietpi or Plex to make sure its caching to the sata drive and not the usb 2.0 drive ? I know where to change the plex transcode folder location but is there anything else needed to ensure i get the full benefits of the sata drive speeds ?