assuming you use chrome, electron will reuse the chromium libraries, so the net increase on memory is not that large. with Tauri, it will have to spin a new set of (memory hungry) browser libraries(i.e. libwebkit2gtk on linux, similar stuff on Mac and Windows) that are all new memory usage on top of chrome(nothing to share), not to mention the libraries Tauri uses are not as "modern" as Chromium on html5/css/js/webapi support.
I still feel Electron is the best approach now.