Last time I checked Samsung tablets and phones, they lagged already in the store. I don't know whether it's all the crapware that gets pre-installed, or just inefficient programming. But I think CPU speed might not help them.
My experience is that Exynos hw was great... but Samsung software (including drivers) was problematic.
Combine to with legacy of android design going for flexibility, including allowance for inefficient options (especially important in comparing graphics - Several Apple models ran on edge of being able to paint one frame without stutter assuming well-optimized code - Apple spent a lot of time ensuring you didn't see that) and you get certain reputation.
The only thing that I noticed really problematic is graphics intensive software optimized for Qualcomm.
Also, the real issue is not that Samsung doesn't have the capability. A lot of Apple "secret sauce" is that they don't have contractually separated design teams that have to "shop" around for suppliers/buyers, which means that both Qualcomm and Samsung are forced to make more mediocre CPUs because it brings wider selection of buyers - whereas Apple can design device with SoC together, which let's them easily take decisions like "ok, let's put A LOT MORE L1/L2 cache on each core" because they aren't going to deal with customers not wanting to buy them.
But Samsung has its own huge mobile business. Wouldn’t it be justified to make an OP SoC for their Galaxy Tab(or whatever they sell)? I’m sure their execs are aware of the possibility.
Supposedly they are forced to keep a "chinese wall" strategy due to possible legal concerns. How true that is hard to check, but there seems to be considerable variation and definitely less "design this cpu specifically for this phone" in Exynos line up, except maybe for first Samsung Galaxy S and SGS2.
P.S. Exynos and Apple A-series have common ancestry
But I doubt that shows in light usage like scrolling or opening an app, that's more likely their (lack of) software optimization.