Tested with a release binary and Swiss OSM roads in PostGIS at several zoom
levels (the higher, the less features), values in ms (average over at
least 100 queries):
Level | Before | After | % improvement
-------------------------------------------
7 | 37 | 36 | 2.7
6 | 41 | 38 | 7.32
5 | 48 | 46 | 4.17
4 | 70 | 64 | 8.57
3 | 114 | 109 | 4.39
Not much improvement (I'm quite dispointed, here), but not much change in
the code.
