Strange lag - massive spike only on first game launch of the day, goes away for following games

This is a problem I have had since a little after the new client. The first time I launch the game to loading screen after turning on my computer, I receive a HUGE lag spike. Massive input lag, discord voice stutters, twitch streams freeze, other tasks unresponsive, and it continues until I get into the loading screen. After this, the lag does not occur for any other matches until I restart my computer again. I've isolated to just the game and the lag is the same, task manager doesn't indicate abnormal CPU consumption either. My computer is pretty high end, 4790K @ 4.7GHZ, EVGA GTX 980, 16 gigs ram, Windows 10 on creator update (but it was happening before then too). Temps remain normal, CPU & GPU I've looked around and didn't see anyone else with this problem. Any help?
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