If you launch the game in full-screen at 4k and your editor is only got a window at 1080p, that’s already enough to justify the leap from 40% to 100%.
.26 is trash.
.27 may also be trash, I haven’t benchmarks it but you can quickly find out:
If you package the 3rd person project (for publishing so no dev. Which means you should manually output fps via a widget), and run it full-screen (4k 1080ti), but you get anything less than 120fps… guess what. .27 is also trash
Turn off the engine, even exit it completely when running the game(s) you publish.
The engine renders, as such it places load in on both cpu and gpu when it’s on screen.
It is rather commonplace to minimize it, or exit it, when benchmarking.
Also, every additional open editor window puts drag on rendering. So when benchmarking in PIE you want to make sure no other editor windows are open.
To have an idea of what you should expect in terms of ms or fps we would have to know your GFX.
And actually own or have profiled the same model.
If you are on a 1080ti, at 4k you can barely reach 80fps on a decent and properly optimized project.
In fact, it’s so rare to see things made with unreal run well that when it happens we tend to praise the developers - outerworlds is a decent example there.