Replace Formula Links-very slow

This thread is related to this thread:https://www.excelforum.com/excel-pro...ula-parts.html
I can't post the workbook, because it's a huge beast with many interconnected parts.

What I want to do is change "2017/2017 05 May" to "2017/2017 06 Jun" (the values will change from month to month, but this is the basic operation).

There are approximately 33K Vlookup formulas in the workbook that would be affected by the change, and they exist on only 2 tabs. However, there are over 100K vlookups total in this workbook, and many tabs, and I think my macro is causing all of them to recalculate. Running the code below takes a full hour to complete, and there's got to be a better way.

I've noticed that if I comment out the "SpeedOff" macro the process completes quickly (because no calculation is happening, so no formulas are refreshing). So, I'm thinking if I could limit the calculation to only those two tabs it would be a quicker process, but not sure how to do that, and not entirely sure it would do the trick. I'd sure appreciate any help I could get on this.

Here are the two links I'm wanting to change (these are the ones the macro is using this time):

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Hi again,

How long does the workbook take to recalculate if you edit the links manually?

xlnitwit,
How do I update links manually?

Kramxel,
There are 20 different source files. I think having all of them open may cause even more issues.

queuesef,
I didn't know that Index/match formulas were less taxing on memory. Do you know of a quick way to convert hundreds of different Vlookups to Index/Match combinations?

On the Data tab, click the Edit Links button, then change the source workbook(s) there.

I think I've spotted my problem, and it really is my problem. in testing, I was changed the links from 06 Jun to 05 May and back again. The problem was one of the workbooks didn't exist in May, so I think the slowdown was trying to resolve that. I'll do more testing and confirm.