I'm sitting here resting a while before going home. Don't like this warm weather. Get easily sweaty. Maybe you can give me advice about two things?

I have to walk 4 kilometers to get home, and there are no shadow. Today it's 90 degrees in the shadow, and no wind. I've often been wondering about this:

1. Here I have a pair of sandals with the weight 100 gram, and sports shoes with the weight 400 gram. What is best for me: to carry the light sandals and walk in the sports shoes, or carry the heavier sports shoes and walk in the sandals?

2. Shall I walk fast at 10 kilometers per hour to spend as little time as possible in the sunshine, or walk more slowly at 5 kilometers per hour since that isn't as strenous?