Sounds like a badly optimized install then. Unless you are running a disk check, or have a hardware raid controller, on every boot, getting a kernel and the minimal environment to run a web server up should take under 1/10 of that.
So with a whole bunch of additional optimisations (not out-of-the-box) you can get an order of magnitude improvement. Unikernels are at least another two orders of magnitude faster than that (~300ms), without any optimisations.
