Calculating Differences -?

While playing a ranked match earlier today, I started to lag and was met with constant "reconnecting". After ~20 seconds, LoL crashed and loaded up the PvP client. However, the PvP client had the "Reconnect" button grayed out and unclickable. I closed the PvP client, and when I reloaded the client it said "calculating differences" - it has been doing that for ~8 minutes at the time of posting and only scanned 640 files. At this point the ranked game I was a part of is essentially over. I have 18 megabits per second internet via Suddenlink - I wouldn't have minded the disconnect but I am concerned about being unable to reconnect via the PvP client / calculating differences upon loading into the game.