According to Ingress, the cooldown times of Portals has been lowered from 5 minutes (300 seconds) to 3 minutes (180 seconds). This may not be readily apparent because of the different timer values that are displayed, i.e. your timer will display 240 seconds but in reality it will already be closer to 120 seconds. This update is temporary and may coincide with the Cassandra anomaly, if so, it may end on the 24th.
Heat sinks are affected by the cooldown change, but the only difference is in the math, If you visit our heatsink page, you can get the percentages yourself and apply them to the new Cooldown time.
2 VR HS = 1-(1-0.7)*(1-0.7/2) = 80.5% = 58.5s cooldown time would be changed to having a 36 second cooldown time (80.5% of 180 is 144.5 seconds = 36.5 second cooldown time)