i have done a coding in shell scripting which reads a file line by line and does something....it takes more than 30 seconds to execute for a single file. when i do the same with perl scripting it takes less than a second.
is that shell scripting is not efficient while working with large number of files?

Apparantly, you did a better job when you used perl than when you used a shell. Shell scripts can run very fast provided that you use a decent shell. No one can say why your script is slow without seeing it.