It seems you are using the MAX V to do passive configuration, whether with SPI NOR or Parallel NOR flash. I have seen customers who implemented such scheme with S29GL-S or S29GL-T devices, i.e. Parallel NOR. For SPI NOR, such as S25FL-S or S25FS-S, most customers use them in Active Serial (AS) configuration scheme, without the MAX V CPLD. But certainly they can be used with the MAX V also as long as the CPLD can read out data from the SPI NOR.
Regarding to the speed, you may need to do some calculations based on your particular system to see what the maximum read throughput you can achieve. For SPI NOR, it mainly depends on the clock speed and number of IO you are using. For Parallel NOR, it depends on whether you can make use of the Page Read function that reduces the initial access time for each read.
Hope this helps a little bit in your consideration.