Comparing FPS is not very meaningful. The difference between 922 and 900 FPS is very small; the difference between 25 FPS and 3 FPS is huge.
Translate to “frame time” instead. If 143 instances of tree A take 15 ms, then you can assume another 143 instances of tree B would take another 15 ms, and you can calculate your final FPS based on adding up the different numbers (within reason – because of pipelining, some micro-benchmarks end up overlapping and costing less in real projects.)