Currently if the exchange rate in CRM is updated, the base currency on active records won't be updated to reflect this meaning that calculations performed on the base currency field will typically be incorrect.

To resolve this we need a mechanism to force a base currency recalculation on all records where a currency field is present and contains data. This job would need to be scheduled out of working hours due to the impact on the user experience during this time.

This is most present directly in CRM when a chart is used. I.e. In a dramatic example to highlight the issue:
Day 1, Exchange rate (e) = 2.
New Opportunity (A) -Local revenue (l) is 1; base currency (b) is 2.

Day 2, Exchange rate (e) = 4.
New Opportunity (B), local revenue is (l) 1; base currency (b) is 4.

Day 3, Exchange rate (e) = 8.
New Opportunity (C), local revenue is (l) 1; base currency (b) is 8.

The user would expect the sum of their opportunities to be (Al 1+Bl 1+Cl 1)=3 but the chart would return ((Ab 2+Bb 4+Cb 8)/e 8)=1.75.