Increase speed performance Wordpress website with multiple plugins (Woocommerce)

Dear IT friends, I need some help with improving the speed and loading page of a project. Hereby some details:
- Wordpress website (latest version)
- Woocommerce webshop
- Multiple plugins installed
- Xstore template used (https://themeforest.net/item/xstore-responsive-woocommerce-theme/15780546)

Assignment:
I am facing long loading times for the website. Pages load very slow. This needs to be improved. I need support in finding a solution and pointing out the problem.

Requirements:
- For this job I need a person who has EXPERIENCE with this.
- The job needs to be done on a LIVE WEBSITE, so be aware this is NOT a development website.
- We can't afford any downtime, so first we need to do some testing and research on the issue.
- So no trial-and-error can be done...

Reward:
- Before you start working on a solution we will do a speed test.
- After your work is done, we will do the same speed test (same service).
- If you managed to increase the speed/page load the reward will be released and given.

Please specify your approach in your quotation and experience with this. I am aware of the minify feature of javascript and stylesheets which many plugins offer. But I think/feel the solution is somewhere else. I have already installed a caching plugin as well.

Finally. Have a look for yourself and please visit bombthebrand.com to check and see.