cc Marley Kudiabor - for following up, some questions for you: 

• Your non slow jenkins server - if you update that to rc3 - does it then slow down? 
• If you downgrade the slow server to an older release, does it speed up?  (if so, which version?)
• If you load the slow page again, does it take 60s or 1 minute or less for subsequent loads? 
• Is the "classic" dashboard slow or other pages slow in any way on the slow server?

Just trying to narrow down if it is due to plugins/environment for the slow jenkins, of if it is something introduced in a blueocean plugin. Unfortunately there may not be enough information to go on in the har file (there may be some URLs we can try if Vivek Pandey suggests anything). This is a very small number of jobs and many people use it with 100s or 1000s, so this is quite odd. 

Further more, you could use the https://wiki.jenkins-ci.org/display/JENKINS/Support+Core+Plugin plugin to provide extra data as to what is running and what are slow requests etc, if this isn't enough, but the above questions would be most helpful to answer. 

Vivek Pandey would you suggest any experiments on that search query that may hint at what is causing the slow down? 

Unfortunately today isn't the best day to update the jenkins server itself. Blue Ocean was updated to rc3 though and it was still slow before and after. I believe previously it was on b23 or so?

The slow page takes about the same amount of time to load on first load and sequential loads with or without caching.

The classic dashboard is still very snappy.

Attached is a log file from after a long load. 
Please email me directly for the password. I've emailed those already mentioned in this ticket the file and password pre-emptively

On Analyzing HAR file, looks like Job config history plugin actions are causing this slowdown. Brief look at this plugin code tells the history is not cached so each history item results in to read from file system. I could reproduce it locally where just couple of freestyle jobs with config history of in 30 or 40 resulted in almost 8 to 9 times degradation.

Marley Kudiabor is it possible for you to set max number of config history visible per page to lets say 5 or so to see if it makes difference. At least it will validate the theory. You can find it at  Manage Jenkins->System Configuration -> Job Config History -> Advanced -> Max number of history entries to show per page.

At present going over favorited items (26 of them) have config history items all the way from 3 to 143. 

Here are the size of job config history items per pipeline.

[17, 3, 7, 3, 11, 11, 4, 30, 143, 14, 4, 7, 3, 8, 4, 12, 13, 24, 4, 20, 4, 11, 9, 53, 17, 11]

On blueocean side of things: Actions could bring such performance issues as blueocean currently is fetching them eagerly, which is bad. To fix it we need to have UI provide filter using tree api of search (/blue/rest/search API). Prefetch is different, here it's server side generated HTML with generated favorite list, it needs to be fixed so that it processes UI provided tree parameters in /blue/pipeline/ HTTP call to generate list of favorites.

Unfortunately neither decreasing history objects or even completely removing the config-history folder from %JENKINSHOME% affect the lag. Perhaps the problem is somewhere else in my configuration.

I'll be off work until Monday so I apologize for any delay in response until then
 

The job config history plugin is infamous for introducing problems in various places (unless you use ramdisk, rarely save changes to config), so this isn't too surprising. 

If you dont' want to remove it (you probably have it for a reason), then there will be a fix coming, and blue ocean shouldn't be slowed down by this either. 

The fix in summary: 

• don't just fetch everything about a pipeline just in case it is needed 
• don't return history data that isn't wanted anyway

One of these should land soon (one is a longer term, one is a shorter term enhancement).

Thanks! 

Modified path in description to remove our jenkins domain from google search results

Repoening because the issue is not fixed.

As Marley Kudiabor wrote, the config history plugin did not cause the long loading times.

I am experiencing the exact same issue, opening blue ocean takes 18 seconds for us on a very fast server. Deleting the config history did not help.

I've noticed that the dashboard loads quickly when I'm not authenticated.

Jenkins version 2.46.3, BlueOcean 1.1.2

Hans Schulz it would be better to open a fresh ticket than re-open this one with all the noise as this isn't related to config history plugin (likey another plugin, or number of favourites, could be a lot of things).

Then can chase it down. 

Hans Schulz please open a new issue and email me a HAR file for the page load at jdumay@cloudbees.com

If you are a CloudBees customer you will get a better turn around by filing a ticket at support.cloudbees.com and attaching a the HAR file there.