Which Shopify speed optimization app should you install?

The word speed covers five jobs

A Shopify speed optimization app is any App Store listing that promises a faster store, and the listings under that phrase do different work. One writes critical CSS, which is the small stylesheet the browser needs before it can paint, and then minifies the rest of the theme. Another compresses images and adds extras such as alt text and JSON-LD. Another prefetches the next URL when a shopper hovers a link, so the following page has already started downloading.

Another sequences third-party scripts so they do not run until the product photo has painted, and another sells monitoring of real visitors and, on a paid plan, sequences scripts. We make Whoosh, so Whoosh is in the table, and the table is there to show which of those jobs each listing actually does.

Pick the job that matches whatever is sitting in front of your product image, which you can see by reloading a live product URL and noting which file finishes before the photo. The word speed on the listing does not tell you that.

Listings were checked on 21 Sep 2026, prices below are USD per month on the public Shopify App Store, and good Largest Contentful Paint is 2.5 seconds at the 75th percentile of real users. Two tools that both claim speed will fight when they try to delay the same script, so match the mechanism to the bottleneck before you install a second one.

Six listings

Dimension	Whoosh	Hyperspeed	Thunder	TinySEO	Booster	Yottaa
Mechanism	Script sequencing, LCP preload, next-page prerender	Critical CSS, minify, lazy-load, image compression, JS defer	Defer JS/CSS, critical CSS, image compression, preload	Image compress, lazy-load, JSON-LD, ALT, redirects	Hover prefetch of the next URL	RUM, then paid script sequencing
Theme copy	Does not copy the theme	Listing includes theme edit	Preview before publish	Theme edits for images and SEO	App embed	Optimize sequences apps
Proof	50/50 conversion A/B on your store	Lab PageSpeed and GTmetrix	Daily Lighthouse; field vitals on the US$69 plan	SEO audits and image counts	Faster next click on hover	RUM dashboard
Public price	US$99 or US$149/month, 7-day trial	US$59/month, 7-day trial	Free; US$19.99; US$69 (500k, then US$10/100k); US$199	Free (50 images); US$14; US$23; US$49	Free	Insights free; Optimize US$300/month under 150k pageviews, 14-day trial
Where they are stronger	Conversion A/B, no theme copy	Critical CSS, US$59, 174 ratings	Free tier and critical CSS	Images, SEO extras, 2,506 ratings	US$0	Enterprise RUM, 14-day trial

What the cells do not spell out

If the thing blocking first paint is render-blocking theme CSS, Hyperspeed or Thunder is the listing that matches, because both ship critical CSS and Whoosh does not. Leave a theme-writing app in preview until checkout and the forms still work, and do not run two minify passes, or two critical-CSS passes, on the same theme. Two writers editing the same stylesheet is how a form breaks even when each listing looked reasonable on its own.

Do not let two apps defer the same tag, because if Hyperspeed and Whoosh both delay one marketing script, the form can mount late or twice. Give each script one owner, then tap the form, the chat, and add to cart on a phone, and never defer Shopify checkout scripts or payment scripts. TinySEO on images next to a sequencer is a reasonable pair, because one owns pictures and schema while the other owns when third-party scripts run.

Pageview arithmetic matters for Thunder’s real-user vitals plan and for Yottaa Optimize, because those prices change with traffic. Whoosh plans are a flat monthly rate on the Whoosh App Store listing, so the price does not change at 100k views or at 500k views, and you only do that arithmetic when the listing meters traffic.

Check the product page you sell

Open a live product page rather than the theme editor preview, which often hides the embeds you are trying to judge. In Chrome DevTools, open Network, disable the cache, throttle to Slow 4G, and reload. Filter to JS and count hosts that are not cdn.shopify.com and not your own domain. A sequencer might delay those hosts, while a tool that only minifies CSS will leave them on the critical path, still running before the photo.

Switch to the Performance panel, record a reload, and click the LCP marker, which on Dawn is usually the main product image. Note which script-evaluation blocks sit before the image finishes, then toggle the speed app and reload that same URL. You are looking for whether the script moved, or whether the CSS got smaller while the marketing tag still runs early.

In App embeds, toggle the speed app off in a theme preview and reload once, and search theme.liquid for a second copy of the same snippet. A speed app is still an app, and if its own script evaluates before the product image, it is on the critical path too.

Does Klaviyo slow down Shopify is that check aimed at one marketing tag, so you can see whether the optimizer moved klaviyo.js or left it racing the image while the stylesheet shrank. TileCloud recorded a 15% conversion lift, and Nakie cut load time from 4.8 seconds to 1.35 seconds.