I am convinced that for most HA users who experience laggy performance of HA on an RPi 3 the real reason is memory (RAM). HA has evolved to a point where an average installation with some add-ons will easily consume most of the 1 Gb of memory that an RPi3 provides. Even if only some 700 to 800 Mb of mem are allocated Linux will still start to get much slower. The reason is that free mem is used for disk caching. And HA reads and writes to/from disk a lot for its history data.
So the real solution for this problem is to upgrade to an RPi4 with 4 or 8 Gb of RAM. I have done that and my system flies! You can use my extensive installation guide to get HA running on an RPi4: