There’s been quite a lot of optimisation of the decoder which makes it much more cpu efficient, and improvements to the preamble filtering that means the data you get out should be cleaner.
There is a new option -e which takes an argument from 1 to 20. The higher the number, the more permissive the filter is. The old decoder has an equivalent of -e 5. As you are running on a pi 4, you can increase this to take advantage of the extra cpu power available.
I would suggest starting at a value of 9, which should give a noticeable boost to messages without losing samples. You can gradually increase it to find a maximum level - depending on your local circumstances you may be able to get it up to around 9.7 or so without any loss. More than that is right on the edge in my experience and you can get samples lost, especially overnight.
The other important option added is -w, which is the whitelist score for accepting new planes - the default value is 3. The higher this is, the more messages are required before an aircraft is accepted. Depending in circumstances you might find you still get some bogus decodes at this setting, so a slightly higher one might be required. I’m using 5 and see very few single message tracks now:
Other new options you might want to consider:
-f 2 – this enables error correction of 2 bit errors on location messages. These are likely not quite as reliable, and obj requests that if using it, the -n option is also used so that the messages are sent to the network uncorrected so that software receiving it can decide how to handle it.
If you enable that, you might also need to have --aggressive and --net-verbatim enabled in dump1090, however I’m not sure they are available in the current build of dump1090-fa.
-t sets the number of seconds for the whitelist timeout. The default is 60, which I find is fine - setting it longer means that aircraft that are temporarily out of view have longer before they are required to pass the whitelist filter again.
It looks like you have a very nice range now - some reliable contacts at 240 miles or so.
Edit - I just had a look at your FA stats - that’s quite a huge jump in positions reported!