A couple of years ago, Mozilla announced an ambitious initiative, dubbed Electrolysis, to re-engineer Firefox to add native support for multiple processes. This meant that the UI ran in a different process than all the tabs, add-ons and so on.
There are many benefits to this, better responsiveness, more crash protection, improved security, better performance by using more processor cores and so on.
However, the work basically requires a complete rewrite of many of Firefox's components. Mozilla has been working on this for a lot of time now, but progress has been slow. What's more, there's no end in sight for the work.
As such, Mozilla has decided to put the efforts on hold for the time being and instead focus on other short-term enhancements that would improve Firefox responsiveness.
"[Mozilla made] a decision to put the Electrolysis initiative on hold for the foreseeable future and focus on other initiatives aimed at improving responsiveness in the browser," About lmandel, Electrolysis' program manager explained
"Electrolysis is a huge undertaking. I can’t emphasize that point enough. Converting an established product, like Firefox, from a single- to multi-process architecture requires the involvement and coordination of many teams," he said.
The progress so far hasn't been great. And the required investment to make any progress would be huge for a rather small company like Mozilla. What's more, at this point, there is really no way to know how much effort it would take for the team to reach all of their goals with multi-process technology.
As such, instead of locking up people for an unknown amount of time while working on Electrolysis, Mozilla decided that the work would reap greater rewards elsewhere.
"When looking at the investment in Electrolysis, it is quickly apparent that the talented people working on this program could instead be working on some of these smaller initiatives," Imandel added.