This is indeed a big issue. However I noticed as soon as a ticket gets closed they don't look at it anymore.
Is there anything Spigot would be willing to work on as a temporary solution whilst Mojang resolve this? For instance, run chunk loading more efficiently with better use of resources?
TacoSpigot apparently has found some kind of fix? https://www.spigotmc.org/threads/low-timings-1-9-related.127504/#post-1370450
A really critical issue which lots of owners are facing right now.
That is really terrible news. We've lost so many players already in only a couple of days due to the lag issues. And we're even using the best computers out there. 
and this ? https://bugs.mojang.com/browse/MC-98994
Mojang absolutely must become aware of the problem, ca becomes unplayable when players explore chunks, in any case you md_5 thank you commit you in this problem 
Chunk loading in Minecraft 1.9 is always going to be slower than 1.8 due to switching from flat in memory storage to a variety of differently indexed data pallettes. I have done profiling on chunk loading since the last changes and there is nothing I deem fixable. That's not to say there isn't, but I can't see any actual bugs.