> font-lock-maximum-decoration  elapsed  average
 > 3                             1.999    0.012
 > 2                             1.765    0.010
 > 1                             1.466    0.009
 >
 > In comparison the optimized build with ‘font-lock-maximum-decoration’ 3
 > gets me:
 >
 > 3                             0.409    0.002

These tests actually time scrolling only so they are misleading.  Using
the modified attached file the results below are more accurate: R stands
for the release branch, M for master, and O for an optimized build of
master.  The following number is the ‘font-lock-maximum-decoration’
value - 1, 2 or 3.  So R3 stands for the release branch with decoration
level 3.  The second column is the elapsed, the third the average time.

R3     109.61000000  0.6485798816
M3      79.62599999  0.4711597633
O3      11.516       0.0681420118
R2      23.71799999  0.1403431952
M2      25.35900000  0.1500532544
R1      19.32799999  0.1143668639
M1      20.406       0.1207455621

So there is a significant speed up from R3 to M3 and the speed up of M3
to M2 is by a factor of 3 approximately.  With decoration levels 2 and 1
master is slightly slower than the release branch here.

martin