You an read this to find out about mod_gzip, an external module for Apache.
There can be an issue with mod_gzip, when your website is hit with lots of users, attempting to complete some form-submission and if they do not allow enough time for mod_gzip to send the content to the client machine, then the system call can fail and websites may not load during this. You may find some lines corresponding to the following in apache error_logs :
mod_gzip : TRANSMIT_ERROR:ISMEM:32
You may chose to disable mod_gzip for the particular domain, as long as simultaneous users are attempting to complete the forms-related task.
You can edit the .htaccess file for the domain and pass the following codes :
<IfModule mod_gzip.c>
mod_gzip_on No
</IfModule>
Now, mod_gzip would be disabled for the domain !