C1913,
Your performance problem is not related to format. Single byte read is very slow and SD access has almost nothing to do with read speed. I am not sure why you see a slight difference in read speed, single byte read should be almost independent of the SD or format.
What version of SD.h are you using that accepts "eight.three" as a file name?
You need to read multiple byte into a buffer. You should be able to get a large increase in read speed, at least a factor of ten.
Look at the bench.ino example in SdFat. It can read at up to 400 KB/sec on an Uno.
Edit:
I ran your example with a correctly formatted SD using SdFat and it printed 76140. Not sure why you get such a long time for single byte read.
I ran bench.ino with a 64 byte buffer and got the following
File size 1 MB
Buffer size 64 bytes
Starting write test, please wait.write speed and latency
speed,max,min,avg
KB/Sec,usec,usec,usec
283.37,48164,64,220Starting read test, please wait.
read speed and latency
speed,max,min,avg
KB/Sec,usec,usec,usec
320.92,2056,68,193