[Charts] Initial load time of charts is long

[dlebech]

I think this happens when there are two currencies and it needs to load all the currencies before starting to draw the graphs.

Perhaps it could make an initial render of the charts without currency conversions, just so something happens rather than the spinning logo.

This could potentially turn into a larger overhaul where we store historic currencies or conversions in the redux store, since these really shouldn't change over time.