Yes, this particular matrix adds huge load, but we are okay with it for the flexibility that provides. I am sure we could create a smaller matrix that would still exhibit the same bad formatting, but I wanted to make sure you would see what we see.
Yes, there is a Combination Filter field that can be used to "sparsify" the matrix and only run a subset of the combinations. Depending on how you set it up, the filter can react to inputs to the job so that you have a sort of dynamic filtering. It's a great way to only test subsets when the whole table is not needed. To keep things simple, you can set the combination filter to:
Axis6=="4p"
It will only run the odd rows of the matrix, and if you have run the full matrix before you will see that the even rows still looks like they ran but in reality they are all skipped combinations (you can see by hovering with the mouse). To see combinations marked as "not run" you must not have any record of that combination running, even from previous builds. Just delete all the builds other than the last one and you will see that the even rows are now shown as "not run".
I hope this helps, let me know if you need more guidance.
Another problem we have, that is unfortunately long-standing, is that the icon for skipped combinations is the same as the combinations that ran. I am talking about when opening a specific build, not from the job page.
We used to have green/red opaque for passed/failed combinations that ran in this build, green/red "faded" or partly transparent for combinations that didn't run in this build but ran in some previous build, and a grey icon for combinations that were never run. Jenkins moved away from that a while back, now it's impossible to distinguish combinations that were successful because they ran in this build ("Success") versus combinations that were skipped in this build but were successful in some previous build ("Success - skipped") , because they all have the same green tick symbol. Same thing happens for failed combinations. Why not assigning the "not run" icon to skipped combinations in the build view of the matrix?
In any case, we were able to get the old icons back using parts of the neo-light theme css, and that worked okay. The reason why I am bringing that up here is that with the new update of either Jenkins or the matrix plugin now we don't get the old icons back anymore, making it practically impossible to understand the matrix results because skipped and run combinations look the same. If it's not possible to have a "faded" equivalent of the red/green icons, could we at least use the "not run" icon for skipped combinations? It would make more sense.