A fast way to open a workbook as read-only

We are running a manual booking system for a short period of time and we tested the shared workbook option however it caused issues when more than 2 users click save at the time after entering date into the same cell.

The users are just to open the calendar to see what is available and then close it. Its then pretty much real time. However accross the network all users opening is running slow.

Also there are no formulas being used.

But you said that only one user make the changes, so why would 2 people ever save data in the same cell? The 19 users just need to hit save for the master users data to become visible? I agree that shared workbooks are a bit of a nightmare (We use them all the time) But as long as you have given clear instructions to your staff then it should be ok?

Ok, i'll explain a little more but I dont want to confuse things. Because of the shared workbook issues, I now have 1 person making all of the booking requests. The person on the phone opens as read only to see the availability and sends a message to that 1 person to make the booking.