1. Image Optimization : User Proper size images in website. Do not use bigger size or small size image unnecessarily.
There one online tools available for optimize images online. after upload image add Alt, Title tag to images
2. Reduce the Number of High-Resolution Images.
Use minimum high resolution images like 1 to 2 images in slider. not more than that.
3. Choose a Fast Theme.
At the time of choose theme choose SEO friendly and responsive theme according to your store category.
4. JavaScript and CSS files Optimization
Remove un-used  java script, Note some script dependency with other functionality. Keep backup before make changes in Js and Css.
5. Manage the Apps Installed
Remove unused apps, Use updated versions.

6. Better Server Response Time.
Optimize server response time this depends on all above task. Monitor it and try to improve the server response time.

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