Formula in A4 of 16 wrkshts in wrkbk showing that tabs name File opens slow Macro better?

Have a form to post activity on a job.
I keep all of the current jobs in one workbook - each with their own worksheet - and a one word job name on each tab
To minimize the chance of someone posting to the wrong tab I have a formula in A4 showing the job name (tab name) of that worksheet.
Works, but it takes forever to open.
Note - Every week jobs are removed from the workbook, and every week new jobs are added - average about 16 tabs but has gone to 32.
Would a macro help speed up the opening?
Thank you!