# V1.5.0 (development) is released

**URL:** <https://openfhe.discourse.group/t/v1-5-0-development-is-released/2283>\
**Category:** Announcements\
**Created:** [February 26, 2026, 9:26pm UTC](https://openfhe.discourse.group/t/v1-5-0-development-is-released/2283 "2026-02-26T21:26:37Z")\
**Posts on this page:** 1\
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**Author:** ![ypolyakov](https://yyz1.discourse-cdn.com/flex031/user_avatar/openfhe.discourse.group/ypolyakov/32/47_2.png) [@ypolyakov](https://openfhe.discourse.group/u/ypolyakov)\
**Post date:** [February 27, 2026, 8:52pm UTC](https://openfhe.discourse.group/t/v1-5-0-development-is-released/2283/5 "2026-02-27T20:52:09Z")

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I would like to add some clarifications because there are two major optimizations for CKKS bootstrapping in v1.5:

> [@ypolyakov](#):
>
> - Optimizes CKKS bootstrapping and polynomial evaluation for multithreaded scenarios ([#908](https://github.com/openfheorg/openfhe-development/issues/908))
> - Adds a new mode of CKKS bootstrapping that achieves a smaller latency and higher precision ([#1074](https://github.com/openfheorg/openfhe-development/issues/1074))

@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](https://github.com/openfheorg/openfhe-development/blob/main/src/pke/examples/CKKS_BOOTSTRAPPING.md) (the relevant flag is `BTSlotsEncoding`). An example of the new CKKS mode is provided in [the updated simple CKKS bootstrapping example](https://github.com/openfheorg/openfhe-development/blob/v1.5.0/src/pke/examples/simple-ckks-bootstrapping.cpp#L172).

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](https://docs.google.com/spreadsheets/d/1iYrNDTx-qwYO8kvRpFfTnqOGeUK0pwc4NLwO9VTH7Lg/edit?usp=sharing). 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.

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