This proposal from the High Performance Working Group provides a FIX session layer for high performance. FIX Performance Session Layer (FIXP) is a lightweight protocol designed for high performance use cases.
FIXP Version 1.1 Release Candidate 1 adds a usage guide for sessions over WebSocket, a popular web-based messaging protocol.
The technical standard specification for the Version 1.1 Release Candidate 1 for the FIX Performance Session Layer can be found here: https://www.fixtrading.org/standards/fixp/
The proposal is following the technical standards review process described in the document found here: https://www.fixtrading.org/packages/technical-standard-proposal-process/
This release candidate now enters a public comment period in which public review and feedback is encouraged. The public comment period will run for a period of 90 days beginning on the 10th of January 2019.