Smush plugin review and common issues

Smush marks images as already compressed once they have been processed, even if the size reduction was minimal. This commonly happens when images are already well-optimized before upload, when lossless compression has limited effect on a specific image type, or when the 5MB limit prevented processing. To check: in Smush → Bulk Smush, images that were processed but saw little reduction appear as optimized. If your images are above 5MB, they are skipped entirely in the free version — consider resizing before upload or upgrading to Pro.

Lazy loading delays image loading until near the viewport — this conflicts with JavaScript-controlled sliders and carousels that need images pre-loaded. In Smush → Lazy Load → Advanced, you can exclude specific images by CSS class, ID, or URL. Add your slider’s image class (e.g., swiper-slide img or slick-slide img) to the exclusion list. If you are unsure of the class, inspect the slider in browser DevTools. Excluding slider images prevents the lazy loading conflict while keeping lazy load active for gallery and content images.

Smush’s WebP serving requires either server-level configuration (Apache .htaccess rules or Nginx config) or the CDN delivery method. If using the local file method, check that your server’s .htaccess was updated by Smush — go to Smush → WebP and verify the server configuration status. On Nginx, the .htaccess method does not apply — use Smush’s CDN delivery option instead, which serves WebP automatically via browser detection regardless of server type.

In Smush → Settings → Image Sizes, you can select which WordPress-registered image sizes to compress. By default, Smush processes all thumbnail sizes generated by WordPress (thumbnail, medium, large) plus the original. Deselecting certain sizes skips their optimization and reduces the number of API calls used. For most sites, optimizing all sizes is recommended. If your theme generates many custom sizes, deselecting unused sizes keeps your API quota available for the sizes actually displayed on the site.

Yes. In Smush → Settings → Resize Original Images, enable automatic resizing and set maximum width and height dimensions. When an image exceeding these dimensions is uploaded, Smush resizes it before compression. This is useful for preventing users from uploading 6000px-wide photos to a site that never displays images beyond 1200px wide. The original (oversized) file is replaced — enable backups first if you want to preserve originals.

For a typical blog with moderate image volume and standard photo sizes under 5MB, Smush free is adequate. Auto-smush and lazy loading are functional and require no ongoing effort. The compression quality limitation compared to ShortPixel or Imagify will result in slightly larger image files, but the difference is not always perceptible to end users. If image performance is a priority or you upload many high-resolution images, the better compression rates of ShortPixel or Imagify are worth considering.

ShortPixel consistently delivers stronger compression on JPEG product images — particularly relevant for WooCommerce stores where product images are numerous and central to the shopping experience. ShortPixel also supports AVIF format and lacks Smush’s 5MB per-image limit. For stores prioritizing image performance and page speed, ShortPixel or Imagify are stronger choices. Smush remains a good option if the site is already committed to the WPMU DEV ecosystem.

Yes, that can happen, especially on older sites with many plugins. This usually happens when the plugin, theme, and add-ons are updated out of sequence. In most cases, testing on staging catches the issue before it reaches the live site. From experience, backups and changelog reviews save a lot of cleanup time.

Start by checking whether another plugin already does the same job. In most cases, overlap is what creates avoidable conflicts and performance issues. A common issue is installing a plugin because it looks convenient without checking the stack first. From experience, a short compatibility review avoids most of the pain later.