Re: Firefox ESR large text file rendering problem
This problem is now solved.
The problem was that "offmainthread" rendering requires that SKIA 
graphics library must be compiled-in at compile time.
In firefox-45-esr SKIA appears to be disabled by default, and requires
opt-in at compile time to enable it. "offmainthread" is enabled by default
(but can be disabled by about:config entries). By using all defaults, you
end up with incorrectly working Firefox binary.
In firefox-52-esr SKIA appears to be enabled by default, and can be opt-out
at compile time to disable it. "offmainthread" is hard-coded-enabled. By
using all defaults, you end up with correctly working Firefox binary.
My problem with firefox-52-esr builds was that I had these in my .mozconfig
Jari Ruusu 4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD ACDF F073 3C80 8132 F189