runtime.gogc configures GOGC (the GC target percentage).

Setting runtime.gogc is equivalent to setting the GOGC environment variable which also takes precedence over the value from the config file.

Increasing this value means fewer but longer GC cycles since there is more garbage to collect.

NOTE - the default for fabio up to 1.5.14 was 800. This changed to 100 in version 1.5.15

The default is

runtime.gogc = 100