It might be the audio peaks loading (as Vegas calculates and draws the visual waveform peak files), but it’s certainly easy to check: During the long load, in the lower left part of the interface, you should see a Cancel button and a progress bar moving from 0% to 100%, with the notation “Building peaks for…” and the file name. You can hit Cancel (or press the Esc key) to stop this on a case-by-case basis (it won’t effect anything, you just won’t get to see the waveform and clips will have “(Peaks not available)” on them instead).
There are some Preferences you can toggle that might help. Options > Preferences > General tab > Build peaks for visible events only, for example. If your 60 minute clip is on the timeline, then this won’t matter. You can also set Vegas to use half-resolution peak files with Options > Preferences > General tab > Build 8-bit peak files.
However, once the peaks are built, they won’t need to be redrawn from scratch every time and loads should be relatively fast, so I’m thinking this isn’t your problem.
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Television is the first truly democratic culture – the first culture available to everybody and
entirely governed by what the people want. The most terrifying thing is what people do want.
— Clive Barnes —
https://videopia.org