Retrieving data from S3 is very slow

In my application i use S3 to store user data. User has files and each file has its id and i need to store for each file its data and a snapshot image (png). I store the data in the following architecture:

file.data file.png file.data file.png file.data file.png

My problem is that retrieving the files from S3 takes a lot of time. It can take about a minute to get 5 png files.

What can i do to improve S3 performance?