Upload to S3 takes time long

[emptyfist]

I made a simple Job with Laravel framework v10.

This Job scan all files from source directory and uploads to S3.
When I put over 1000 files(each file over 10MBytes) to source directory and try to run the Job.
(Server runs on EC2)

At first, each file uploading takes 1020 seconds but when files uploads further, uploading time getting slower.
After 100 files uploaded, uploading time per each file takes over 56 minutes.
What's the wrong?

Uploading code is as followings

foreach ($files as $file) {
   $fileName = pathinfo($file, PATHINFO_BASENAME);
   $disk->put($publicPath . '/' . $fileName, file_get_contents($file));
}

$disk is the Storage class's instance which indicate s3.