For the first question, the following support doc may be of use:
PBCS: Long Running Rules are Not Executed in the Background (Doc ID 2339756.1)
For the second, if you are sure the rule is calculating the same amount of data, creating same blocks etc but the running time is widely different then you should take it up with Oracle as they manage the service. I would expect such fluctuations if everything is the same each time the rule is run.
You should also be able to see in the activity reports if there are high utilisation on resources, though it may not tell the full picture as that might just be virtual machine and not the resources on the host.
On the first one as an enhancement request is there any way to add your vote as a an Oracle customer to give it more 'weight'?
Understood on the second.
Thanks again you are a treasure to the EPM community, we all owe you big time,
I suppose you could log an SR, the more SR's they get then hopefully it will move faster.
Okay, you have more faith in SRs than me but it is worth a shot!