@whytwo I have seen no (real) performance benchmark yet to compare Grav with other database-based CMSs. And as others said performance is impacted by other factors. Clearly and if you want to compare things, you must run both on the same webserver. Secondly, they must provide the same functionality. Wordpress and Co are much more feature rich, but most of the core features can be disabled. Further (and if you want to be fair) you have to switch on caching for Grav and use a caching mechanism for the DB-CMS, too.
If you do that, I'm pretty sure you won't see much differences at all. I really don't know where the speed factor of 10X+ @rhukster is mentiong is coming (sorry @rhukster, but I have seen no prove of it yet). But it will definitely not that much and will differ on your test cases.
Usually DB-CMSs crawl their data and the page from a DB. They don't need powerful SSD at all, but can be boosted with them, too. Databases are constructed to be highly packaged, fast and optimized for low memory usage. Grav instead relies on a fast file system. It has to iterate ove r all files to construct the cache. Thus, the hard-drive is the penalty here and speed due to (random) reads of the disk is important.
Other than DB CMS, Grav loads the whole routing and page structure informations for every page request into memory. For lots of pages this can result in high memory consumption and speed is degradation due to the mentioned above penalty, too. DB CMSs just do a (simple) fetch and don't have to load all data into memory and that's all.
In the end it is a matter of taste, why you are using file-based or databased systems. Both have cons and pros. The only thing you really have to take care of is to use a CMS, which is stable, has a big/good community and uses much of the new features (compare e.g. PHP7 with PHP5.6) of the system to improve the overall speed and performance.