Lower epoch I/O time by 2-3x

[ValarDragon]

Closes: #XXX

Description

Quick fix to improve I/O time. It will instead take more RAM, but this is expected to be minimal

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[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (v4.x@fe9f8b1). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             v4.x     #561   +/-   ##
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  Coverage        ?   20.15%           
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  Files           ?      164           
  Lines           ?    23165           
  Branches        ?        0           
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  Hits            ?     4669           
  Misses          ?    17743           
  Partials        ?      753           

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[ValarDragon]

This worked through Epoch succesfully on my node. (So no state breaks detected)

Cryptocrew and blockpane also tested this version today, with it working and great notes wrt performance:

going to merge!