Javascript code deferral and basic maintenance

I am looking for a freelancer who can help with deferring Javascript code and do basic maintenance for my Shopify website. Specifically, we need help with product pages an you should speed up the load time of homepage. In addition, we also require website speed optimization to ensure that the website runs smoothly.

Ideal skills and experience:
- Experience with Shopify
- Strong knowledge of Javascript
- Familiarity with website speed optimization techniques