As for speeding up during use, that is something I'm seeing as well — even when using the "speedtest" app, after 3-4 seconds you can see a definite increase in speed, but then it seems to hit that 30Mbps limit and never exceeds it.
As much as I wish I could diagnose that to my earlier problem, I think what Zacharias said is important.
Try disabling all bands and test one at a time to get average RSSI, RSRP, SINR, RSRQ and optionally CQI + RI under load.
Sometimes a lower power (low RSRP but good RSRQ) band will be more responsive due to less crowding.
B20 (800MHz) is usually quite saturated but of course this depends on the area the tower is serving.
B7 (2600MHz) is normally for short range/high density coverage so if this is negotiated as your primary CA2 band then you might have slow throughput until traffic is shifted onto B3 (1800MHz) either by tower decision or the LTE6's firmware decision.
Or it could be that your B7 signal is just at the threshold with served density + distance giving you poor throughput.
That's the scenario I experience with B20 + B3 CA2 aggregation and I've verified the throughput issue by using a USRP E312 to watch traffic gradually decrease over B20 and increase over B3.
Also, your output indicates an RI of 1. An RI of 2 here would be ideal for CA2.
To be highly reductive of the LTE standard
, an RI of 1 means UE is receiving downlink data from eNB in TX Diversity mode.
An RI of 2 means UE is receiving downlink data from eNB in MIMO mode. This is the only case where CA2 really shines.
There's a lot to consider here but for stability reasons, I'd try testing each band independently and looking at both speed test throughput and overall responsiveness.
Maybe you're just negotiating the wrong CA2 band pairs and you can test this by disabling all but the two bands of a pair you want to test and then testing it.
CA2 can double throughput under ideal conditions but it can also halve it under less than ideal conditions.
As always, YMMV. Test, test again. See what works!
Edit: clarification on what I meant by lower power band, specific to my scenario.