I did some timing runs for the science collection for V372 versus V3.99.0.9.  This is totally unscientific, so take it for what is meant for - a quick look. First, I ran an ordinary differential equation solver example from the science collection.  This is numerically intensive (which should benefit from the JIT flonum inlining).  It also uses the PLoT package.  The run times are fairly short (so I expect more variance) and I ran it 10 times for both V372 and V3.99.0.9.  The raw numbers are shown below and a simple analysis (using averages from the raw numbers) are at the end.  The bottom line is a 21% speedup in cpu time, an 18% speedup in real time, and a 40% speedup in GC time.  Speedups were computed as (V372 - V3.99.0.9) / V372 * 100%. Next, I removed the graphics and added a loop to run the ODE solver 100 time.  Using the same methodology (but with 5 runs each) gave a 28% speedup in cpu time, a 31% speedup in real time, and a 46% speedup in GC time.  The first run for <a href="http://3.99.0.9">3.99.0.9</a> is significantly faster than the others (seemingly due to the lower GC time),  This wasn't seen in any of the others.  [I probably should have ignored the first run for all of them.] There was also a recurrence of the old problem of an occasional negative cpu time reading from the time function.  I left the output in the raw numbers so you could see it, but didn't use it in the analysis.  I thought this had been fixed a long time ago, but I may be mistaken. So, V3.99.0.9 does seem to be noticeably faster and I was pleasantly surprised that the science collection runs without change on V3.99.0.9.  I know I won't be as lucky for my other collections - I'm one of those heretics that uses (gasp) set-cdr! at times :). ode-example-2.ss w/graphics V372 cpu time: 2450 real time: 2607 gc time: 810 cpu time: 2028 real time: 2054 gc time: 204 cpu time: 2511 real time: 2582 gc time: 859 cpu time: 2043 real time: 2052 gc time: 250 cpu time: 1950 real time: 2019 gc time: 264 cpu time: 2402 real time: 2398 gc time: 624 cpu time: 1950 real time: 1995 gc time: 294 cpu time: 1965 real time: 2047 gc time: 232 cpu time: 1997 real time: 2064 gc time: 312 cpu time: 2371 real time: 2501 gc time: 654 V3.99.0.9 cpu time: 1794 real time: 1906 gc time: 343 cpu time: 1841 real time: 1936 gc time: 358 cpu time: 1528 real time: 1645 gc time: 125 cpu time: 1825 real time: 2003 gc time: 373 cpu time: 1654 real time: 1866 gc time: 281 cpu time: 1669 real time: 1693 gc time: 156 cpu time: 1497 real time: 1618 gc time: 142 cpu time: 1919 real time: 2065 gc time: 452 cpu time: 1810 real time: 1862 gc time: 328 cpu time: 1623 real time: 1728 gc time: 124 No graphics, ode solver 100 times V372 cpu time: 105862 real time: 113963 gc time: 28193 cpu time: 104614 real time: 113527 gc time: 28263 cpu time: 104583 real time: 113608 gc time: 28120 cpu time: 104474 real time: 113784 gc time: 28520 cpu time: -324632 real time: 113562 gc time: 28054 - our old -time friend is back cpu time: 104942 real time: 113705 gc time: 28254 V3.99.0.9 cpu time: 71761 real time: 78887 gc time: 15009 cpu time: 76440 real time: 78641 gc time: 15415 cpu time: 75302 real time: 78292 gc time: 15162 cpu time: 76518 real time: 78341 gc time: 15693 cpu time: 76831 real time: 78569 gc time: 15557 --- Analysis --- ode-example-2.ss w/graphics V372:      cpu time: 2167.7 real time: 2231.9 gc time: 450.3 V3.99.0.9: cpu time: 1716.0 real time: 1832.2 gc time: 268.2 Speedup:   cpu time: 21%    real time: 18%    gc time: 40%   ( V372-V3.99.0.9)/V372*100% No graphics, ode solver 100 times V372:      cpu time: 104895.0 real time: 113717.4 gc time: 28270.0 V3.99.0.9: cpu time:  75370.4 real time:  78546.0 gc time: 15367.2 Speedup:   cpu time: 28%      real time: 31%      gc time: 46%     ( V372-V3.99.0.9)/V372*100% Doug