How to speed up the theme's loading ?

Put the caching plugin in place. FVM is the most effective for optimizing PageSpeed Insight.
Reduce the image's dimensions if at all possible. It is not advised to use photos larger than 1800 pixels. Use an image editor to resize them if necessary, or choose a preset size such as "large," "medium," "thumbnails," etc.Because resizing photos on the fly while using a custom size like 250×250 will increase download time.

Install a plugin that compresses images, such as tiny-compress-images (https://wordpress.org/plugins/). You might wish to start by visiting tinypng.com to examine the quality of compressed images.
Turn on the Gzip compression. You can reduce page size and increase loading speed by utilizing gzip compression. You may find instructions on how to enable gzip and determine whether it is enabled on your server here.
Turn off any unnecessary plugins. For instance, please verify that you have actually built any tables or sliders in the dashboard of any active plugins, such as "The7 GoPricing Tables" or "The7 Layer Slider." Deactivate them if not.

Reduce the amount of Google Fonts you utilize; as more fonts are used, more resources will be required to load, lengthening the loading time.It will happen even quicker.

1. Image Optimization: Compression To reduce the size of photographs without sacrificing quality, use programs like ImageOptim or TinyPNG.Formats: For higher compression rates, use contemporary image formats like WebP.Images that are responsive: Use the srcset attribute to serve images that are suitable for a range of device sizes.

2. Minimize HTTP Requests: Combine Files To cut down on requests, combine CSS and JavaScript files.Inline Small Files: JavaScript and small CSS files are embedded directly into HTML.Minimize Plugins: Don't utilize any plugins that aren't absolutely necessary, and stay away from those that make extra HTTP requests.

3. Content Delivery Network (CDN):To cut down on latency and load times, distribute your content among several servers located all around the world.Make that a CDN is used to provide static items like CSS, JavaScript, and pictures.

4. Caching: Browser Caching: To save static resources on the user's device, configure the appropriate caching headers.Utilize caching technologies such as Varnish, Memcached, or Redis for server-side caching.

5. Minification and Compression:Minify CSS, JavaScript, and HTML Use UglifyJS, CSSNano, and HTMLMinifier, among other tools, to get rid of extraneous characters and spaces.Gzip/Brotli Compression: To minimize the size of files sent to the browser, enable compression on your server.

6. CSS and JavaScript Optimization: Load Asynchronously: For non-critical JavaScript scripts, use defer or async properties.Important CSS. Delay loading other styles and include inline critical CSS for information that is above the fold.Eliminate Extra CSS and JavaScript: Remove any code that is not required to display the page.

7. Server Optimization:Reduce Server Response Time: Upgrade your hosting package and make sure your server is configured optimally.Optimize your searches and make sure your database is correctly indexed.

8. Lazy Loading:Enable lazy loading for movies and images so that they only load when the viewport is accessed.

9. Font Optimization: Make Sensible Use of Web Fonts: Only Include the necessary character sets.Use font-display: swap to prevent invisible text when the font is loaded.

10. Code Optimization: Effective Coding Techniques: Write code that is effective, modular, and clean.Eliminate Extraneous Code: Remove any code that is not necessary for your theme to work.

11. Performance Monitoring and Testing: Utilize resources like GTmetrix, Lighthouse, and Google PageSpeed Insights on a regular basis to assess and enhance the functionality of your website.You can greatly increase your theme's loading speed by concentrating on these areas and carrying out the recommended actions.