The only reason is the lack of time, sorry. I'm too busy with other miners: I released a number of other updates and new miner (NeoScrypt), a few minutes ago I released new version of dual miner.
For this miner I don't see any ways to improve its performance, so I'm going to reduce devfee and apply some minor improvements not related to the speed, but I'm still not sure when I can find time to do it. For example, right now I will have to check CryptoNote miner since afaik devs of Monero will change PoW very soon and that miner will stop working completely, it's more serious reason to update it asap. But I remember about this miner and my promise.
Thanks