I tried that right now, and all of the available options access data within the files so it goes super slow.
I'm attaching a screenshot of my Find command which runs in about a tenth of a second within a folder of 8117 files including 576 JPEG images. The reason it goes so fast is because I am just searching the file name not any IPTC or EXIF data. Essentially all the JPEG images are instantly selected, but as I mentioned there is no way of keeping them together once I start culling them because when I change "All" to "Selected" it works fine until the selection changes to one file (which happens as soon as I start culling) and then all the others are lost. I can tag the selected images to enable me to view only "tagged" images, but tagging also takes forever, and the whole point is that I don't want them to be tagged because I want to either rate or tag only while I'm culling them.
I'm also attaching a screenshot of the idea that you suggested which might work except it doesn't give a way to sort by file extension, only by file name including extension, which takes me right back to the default view.
Note also that I still need the results to be sorted by file name, not just by extension. So what I really need is a filter like Command F, one that can search only the file name so that it doesn't take forever to search through EXIF data, and which also will allow me to keep the results together even while I'm culling them.
I'm sure there is already a way to instantly filter down (or sort as you suggested) the contact sheet to show only JPEG images or to bring them together without needing to slowly search through metadata, while also enabling the results to be kept together while culling rather than falling apart as soon as one of them is selected rather than all of them (which is what happens when I try to keep the Find results together by changing "All" to "Selected").
As of right now, typing Command F and entering JPG and searching only the file name, then choosing "Selected" rather than "All" does EXACTLY what I need, i.e., instant super fast display of only JPEG images together, EXCEPT for the fact that as soon as I start culling the selection changes to only one image and all the others disappear since they're not and then I can't cull anymore.
Nothing else works fast. I've even tried the spotlight search results option. I've even looked for an "Ignore" to "Show only" option for image types in preferences, but there's not one. I think I've tried everything by now.
What am I missing?