Size will surely not reply a floating point number, except if you have shadowed the built-in function by a local variable:
size = rand(10);
tickers = 5;
size(tickers)
You want to copy 3400 files of about 500kB. This means reading writing 1.7GB. When reading and writing happens on the same disk, you can expect the time of writing 3.4GB. When the disk is fragmented, or if it is network drive, 111 seconds are not completely mad.
You mention, that you see a slowdown. Then please explain if you see it between Matlab versions, operating systems, different disks or growing over time, and in the last case, if "time" means minuts, hours, weeks or years. In addition it is important to mention the Matlab version you are using. E.g. old version of Matlab have opened a DOS box to copy files - bad idea.
Please check if the virus checker occupies a lot of computing power during the processing.
You see an extremely slow file handling e.g. short before the final collapse of a hard disk. So please check the disk.
