added performance experiment notes

readme.md

 - Added SOP for installing the latest g++ in ubuntu
 - Added SOP for upgrading libstdc++6 on target ubuntus
 
+iAdditional note: Using RESTsnf as a test jig measured throughput at 8064/minute.
+However, this was only a single data point so only gives us a ballpark, and
+most systems operate at least 2 orders of magnitude below this message rate.
+
+Using the same test jig measured 7960/minute throughput with saccades off.
+Allowed the torture test to run so newer data would be in play and after 5 minutes
+measured 7806/minute. Here are a few more numbers:
+
+.2113 7279.7
+.2114 6084.89
+
+Conclusion is that performance penalty for disabling saccades is not significant.
+
 ## 20200617_M
 - Set up the readme.md file
 - Set up basic build structures for "the new way" of making all things SNF.