Upon upgrading plugin "build-timeout" from 1.12.2 to 1.13, all builds took about 50% longer to complete. This resulted in an unacceptably long build queue and builds timing out. This continued for 6 or 7 hours until an emergency downgrade of "build-timeout" from 1.13 back to 1.12.2 was done, which cleared the problem immediately. No other plugins were upgraded or downgraded during this time, nor were any other system wide configuration changes made.
I suspect the use of "synchronized" in the source code change made writing to the console effectively single threaded for all running builds. (My jenkins instance has 125 slave-nodes, so I have several dozens of concurrent builds all the time.)
Priority: I've made this "Major" because a mere install this plugin version causes my Jenkins instance to be unusable due to slower builds which cause a growing build queue and timed-out builds.
Environment: I'm running Jenkins core LTS 1.532.2 version. I'll be glad to furnish more information as you request it.