I would like to add some clarifications because there are two major optimizations for CKKS bootstrapping in v1.5:
@andreea.alexandru described the second one (issue #1074) and the speed-up she mentioned is for the single-threaded execution for the StC-First mode as compared to the already existing ModRaise mode. BTW, the updated documentation for CKKS bootstrapping is available here (the relevant flag is BTSlotsEncoding). An example of the new CKKS mode is provided in the updated simple CKKS bootstrapping example.
The second optimization is independent and primarily affects the multithreaded execution of the ModRaise mode of CKKS bootstrapping and the functional CKKS bootstrapping (which both existed in v1.4.2). The speed-ups for this case are summarized here. The speed-up for regular CKKS bootstrapping can be up to 2x (on a server machine). For functional bootstrapping (for larger bit sizes), it can even be larger than 2x (on a server machine).
The StC-First mode takes advantage of both optimizations in the multithreaded setting.
Regarding EstimateLogP, I suggest adding a new topic in the Library Questions section, and we will look into it there. This topic focuses on clarifications related to the v1.5.0 release.