[FS#510] slow sysupgrade

[LEDE Bugs]

The following task has a new comment added:

FS#510 - slow sysupgrade
User who did this - psyborg55 (psyborg55)

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no i can't post ouptput, my device runs CC now.

@arjendekorte

at CC this erase after upgrading finish much quicker
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More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=510#comment3400