is the client machine hardware important for performance? or is just the server?  or both ? 

i have been having some troubles in some client machines that crash when sorting records, but i really don't know if the problem comes from the server or client

please let me know 

thank you 

Both.  And all the equipment between the client and the server.

First thing to do is to make sure the FileMaker stats log is enabled (it's off by default), so that you will at least have some objective performance numbers on the server.

Client crashes is not something that is caused by the server.  To start to figure out what is causing the crash on the client you need to look at the crash logs on those clients.  That will point you to the area of FM or the system that causes the crash.

Since it does not happen on all clients, it would seem that is is specific to either the account of the client or the client machine itself.

Make sure all the client machines meet the necessary minimum requirements and that there is sufficient free disk space on them.

Other usual suspects on client crashes:

- plugins

- bad data

Font problems also seem to be linked to client crashes.

Good one, Bruce.  I'm always assuming that people are running the proper v-rev of FM.  First thing to do obviously is to patch FM.

The font problem does not necessarily have anything to to with the FileMaker install and a FileMaker reinstall may not fix it. 

On the Mac, using Font Book to find duplicate or damaged fonts seems to help.

Also, note this thread:

https://community.filemaker.com/message/188569