bug#56682: Fix the long lines font locking related slowdowns

[Gregory Heytings]

> Which one of those CPUs that are 5x slower than the top performer do you 
> consider as being "in wide use"?
>
> AFAICT the highest score there is 4400.  So 5x slower would mean a score 
> below 880.  My 2006-vintage Thinkpad T60 is just below at 848.  But my 
> T61 (released in 2007, tho I bought it refurbished in 2012) is already 
> rated at 1K.
>
> Admittedly, these were top-of-the-line machines when they were released, 
> and are hence faster than many machine released later (e.g. netbooks), 
> but still: I have seen *very* few people recently using machines slower 
> than my T61.

This is more and more tangent, but anyway: I think you should look around 
more carefully.  The Raspberry Pi 4B has a quad-core ARM CPU (Cortex A72) 
whose single core benchmark on that website is 456.  And nowadays "thin 
client" computers, in which slow CPUs are used, are very common both in 
industry and in schools/universities.  One random example, which I've seen 
a few days ago, is the Dell Wyse 3040, which is equipped with an Intel 
Atom X5 Z8350 CPU, whose single core benchmark is 480.