Their is a flaw in the Mintcoin wallet ,
this flaw was only introduced in the latest wallet updates the last devs made.

For some reason, if your wallet has coins in it and you are a few weeks behind, it has a large amount of traffic congestion.
Does not matter if your wallet is locked.

The only way I have seen to bypass this flaw, is to rename your wallet.dat to wallet.keep
, then let mintcoin create an empty wallet and the mintcoin client will sync normally.
Once you have the wallet synced, close the client, rename wallet.dat to emptywallet.dat and rename wallet.keep to wallet.dat and then start the mint client.
Wallet with coins works normally if kept in sync or only a few blocks behind.

If you only mint once a month or so , you have to go thru that wallet renaming everytime, until new devs fix the flaw introduced in the code by the last batch of devs.  


 

FYI:
Use a Snapshot , if your wallet has not been synced in over 6 months, it will be faster.