Salzburg in August - too busy

[Sunholidays]

I'm trying to organise a trip with my mum in August and I'm tempted by 3-4 days in Salzburg. However, I'm worried that it might be too busy with the music festival going on. We'd love to attend one or two concerts, but my mum needs a walking frame and I'd rather avoid crowds if I can help it. Has anyone been to Salzburg in August, and how busy does it get? Thanks!

@Sunholidays we were there during the festival last year and didn't find it particularly busy. Book concerts ahead - I think they are very popular. There are outside screenings in a free seated area too. The cathedral has daily organ concerts at 12.00 which were very reasonable.

Thank you, this is very helpful. Did you do any day trips by train by any chance?

@Sunholidays we spent 4 days in Salzburg and 8 in Zell am See. You could get the train or bus there for a day easily. There's a boat that does a tour of the lake for about an hour. Cable cars up the mountain are expensive (unless you stay and have the summer card) but stunning views. Possibly not a great idea with a walking frame though.
Hellbrun palace and trick fountains were fun. Easy bus ride.
The buses were excellent.