In order to future proof the Lottie format, a steering committee has formed under the governance of the Linux Joint Development Foundation to develop and provide continuous stability to the Lottie format as a web standard and open community project.
It depends on the content of the file and method of delivery, by default most lottie animations have a similar performance profile to rive animations, the only notable difference being that rive animations have a smaller uncompressed file size due to using a binary rather than a text format. However since most files in production are delivered with gzip compression enabled, the size sent over the wire is pretty much indistinguishable between the two formats.