Copying Files: Why much faster using shortcut buttons?

I wanted to create copies of all files in the same directory and have Dopus rename the copies. I tried it in 2 ways:

1a. Select all files (ctrl-a)
1b. Copy all files (ctrl-c)
1c. Paste all files (ctrl-v)
=> Dopus creates copies of all files and renames the copies (e.g. copy (2) of xxx)

2a. Open the directory in two listers
2b. Select all files (ctrl-a)
2c. Click the copy button and select to rename all (new files)
=> Dopus creates copies of all files and renames the copies (e.g. copy (2) of xxx)

For some reason, method 1 is very slow; the files are copied at a snail rate. However, method 2 is on the order of 10 times faster.

Why?

p.s. I forgot to mention that the files are all 0 bytes.

How do I edit a post here..??

Which folders are you copying and pasting from? Is there anything special about them> (e.g. is one a virtual folder like Desktop rather than a real directory?)

Do you get the same problem when using drag & drop to copy things?

What about when using Explorer to do the same things?

My bet is that something is interfering with the clipboard, which could affect drag & drop as well as they use similar mechanisms under the covers.