My SSD specifications say its peak read/write is 550/500 MB/s. What influences the actual speed? Is there any way to make a file that I need to be read fast to be always read at max speed?
SSDs are typically compared using four speed measurements:
The sequential speeds are usually higher than random speeds, because these are sustained reads or writes that can fully benefit from the fact that SSDs have several flash memory chips that can be accessed in parallel. Random reads and writes might only access one flash chip.
In your case, the manufacturer will be quoting optimal sequential speeds: using a large file, with no other operations at the same time.
Two points should be noted:
You should not have to worry about anything on the drive side. On the OS side however, if you are separately reading other files, that could eat part of your 550 MB/s away.
As an aside, as this is something that you typically cannot change, your file will be read/written faster if they are compressable. Credit to @Col.