BigCommerce Speed Optimization
35+ BigCommerce performance sprints completed · 90+ PageSpeed scores achieved
Your store loses sales every second it takes to load
Every 100ms of page delay costs you 1% in revenue. We audit and tune every layer of your BigCommerce stack so your store loads faster than your competitors can react.
0.8s
Average LCP after Redefine tuning
96
PageSpeed score post-sprint
48
Hours to audit baseline delivery
Submit brief → call within 48 hours → audit in 5 days → Sprint 1 within 1 week of sign-off
Capability-specific problems
Most speed fixes treat the symptom. We fix the source.
A generic speed app won't close the performance gap on BigCommerce. Your theme, third-party scripts, images, and installed apps each carry their own overhead. Fixing one layer while ignoring the others gives you a temporary bump, not a real score.
The old way
Install a PageSpeed plugin and call the project done
Compress images once, never revisit the pipeline
Defer every script globally and break checkout widgets
Report lab scores monthly without fixing product detail page
or cart
Optimize the homepage only and ignore checkout paths
The Redefine way
Layer-by-layer audit: theme, scripts, images, and apps
Core Web Vitals targets set before the first sprint
ships
Stencil-specific deferral that preserves checkout and
search
Before/after dashboard with real LCP, CLS, and INP
baselines
Full-store coverage: product listing page, product detail
page, cart, and checkout tuned together
Part of a broader growth plan? See our BigCommerce Store Optimization Services.
Live performance view
See what your store's scores look like after a Redefine sprint
This panel mirrors what we deliver at the end of every speed sprint. Real metrics. Real baselines. No opaque reports.
View:
Live field data simulation
96/ 100
Performance Score
Excellent
All Core Web Vitals passing
GoodLargest Contentful Paint
0.8sTarget: <2.5s · Was 4.2s
GoodCumulative Layout Shift
0.04Target: <0.1 · Was 0.38
GoodInteraction to Next Paint
90msTarget: <200ms · Was 580ms
GoodTime to First Byte
180msTarget: <800ms · Was 1.4s
Optimizations applied
Theme layer: critical CSS inlined
Handlebars render-blocking paths removed
Script layer: 6 render-blocking tags removed
async/defer applied to 14 remaining scripts
Image layer: WebP + lazy load pipeline
CDN delivery, next-gen format conversion done
App layer: 3 bloat-generating apps removed
Checkout script overhead reduced by 68%
Estimated revenue impact
+1.8%
Conversion rate lift
-22%
Bounce rate
+14%
Search ranking
Metrics shown are representative of results across BigCommerce performance sprints. Actual outcomes vary by store complexity, traffic, and existing configuration.
Implementation options
Every layer of your BigCommerce store, optimized
We tune all four layers independently and in combination. Most stores have performance debt across all of them. We address them in order of impact.
Need full development support alongside speed work? See BigCommerce Development Services.
Layer 1
Theme optimization
Your Stencil theme is where most BigCommerce speed debt lives. Handlebars rendering, CSS bundling, JavaScript execution order, and critical path inlining all affect your first contentful paint directly.
Critical CSS inlining
JavaScript bundle splitting
Render-blocking resource removal
Stencil-native performance patterns
Layer 2
Script management
Third-party tags are the single most common cause of BigCommerce slowdowns. We audit every script, apply async/defer where safe, and remove or replace the ones blocking your paint.
Average reduction:
6 to 12 render-blocking scripts
per store
Layer 3
Image pipeline
WebP and AVIF conversion, correct sizing, lazy loading, and CDN delivery instructions. Images are often 60% of your page weight.
Layer 4
App layer cleanup
Installed apps inject scripts into every page load. We identify which apps create the most overhead and recommend removals, replacements, or load-time deferral strategies.
Per-app script overhead audit
Checkout-safe deferral rules
3 to 11 marketplace apps reviewed per sprint, with
remove-or-replace recommendations for each
Core Web Vitals targeting
We set LCP, CLS, and INP benchmarks specific to your traffic patterns and device split, then work toward those targets with measurable sprint outputs rather than generic make-it-faster goals.
<2.5s
LCP target
<0.1
CLS target
<200ms
INP target
Ongoing monitoring
CrUX field data review after every sprint so you know your real user experience, not just a lab score.
Technical approach
The four-layer BigCommerce performance stack
Other agencies run a single PageSpeed test and patch what they find. We work through your stack in a defined sequence because each layer affects the next. Fixing the app layer before the theme layer wastes both of our time.
LAYER 1
Theme & Stencil rendering
Handlebars, CSS critical path, JavaScript execution order
LAYER 2
Script & tag management
Third-party audits, async loading, tag removal
LAYER 3
Image & media pipeline
WebP/AVIF, sizing, lazy loading, CDN delivery
LAYER 4
App layer & checkout scripts
Installed apps, API call overhead, checkout friction
Render-blocking resources8 found
Critical CSS not inlinedYes
JavaScript execution impactHigh
CSS bundle size (gzip)142kb / target: 40kb
Recommended actionSprint 1 priority
Expected LCP improvement after theme optimization: 1.8 to
2.4s reduction
Select any layer to see that audit view. Each layer report is delivered as part of your initial audit.
Proof
A BigCommerce store that grew revenue 3.8x in three years
BigCommerceOutdoor / Sporting GoodsDTC BrandSearch Engine Optimization + Speed Optimization
Off Grid Knives sells premium outdoor knives direct to consumers on BigCommerce. They faced strict paid advertising restrictions in their market and needed performance and organic search to carry growth.
Problem
The BigCommerce store had user experience friction, slow page load, and limited organic visibility. Paid advertising channels were restricted in their market, so every sale had to come from organic traffic and on-site conversion. A slow store in that context directly caps growth.
Solution
A custom BigCommerce store was developed with user experience research driving the build. Page speed optimization was applied through search engine optimization best practices and performance tuning. Store order processing was improved through BigCommerce APIs. Klaviyo became the primary revenue channel alongside organic search.
Result
$3.8M
Annual revenue after three years, up from $1M. Speed and search engine optimization improvements drove higher organic rankings and conversion rates. Klaviyo email became the primary revenue channel. The store now performs sustainably in a restricted-advertising market.
Source: Redefine project records. Metrics are attributable to BigCommerce performance, user experience, and search engine optimization work on this engagement.
Why Redefine
Platform-native speed work, not generic web performance
Most speed agencies run the same Lighthouse audit on any platform. BigCommerce has its own architecture: Stencil, Handlebars, a specific CDN configuration, and an app ecosystem that behaves differently from Shopify or custom builds. Generic advice doesn't transfer.
BigCommerce-native, not generic
We work inside Stencil, BigCommerce's CDN, and its API layer. Not pasted-in advice from a generic web performance playbook. Every recommendation is specific to how your store is actually built.
Field data, not lab scores
Lab scores measure a synthetic test. We track CrUX field data from your actual users, on their actual devices, over their actual connections. That's what Google uses for ranking signals.
Four-layer approach, not a single fix
Theme, script, image, and app layers are audited and optimized in sequence. Fixing one layer and ignoring the others is the reason speed efforts don't stick.
All changes tested before going live
All performance changes are tested in a staging environment and verified against your design before going live. You won't wake up to a broken storefront after a speed sprint.
Audit in 48 hours, sprint in 1 week
You don't wait a month to find out what's wrong. Your baseline Core Web Vitals audit arrives in 48 hours. Sprint 1 begins within a week of sign-off.
No app upsells
We don't recommend installing another BigCommerce app to fix a problem created by too many apps. We remove overhead. We don't add it.
FAQs
Questions before you book
Your Core Web Vitals baseline audit is delivered within 48 hours of access being granted. This includes your LCP, CLS, INP, and Time to First Byte baselines measured against both lab and field data, plus a layer-by-layer breakdown of the highest-impact issues. A full four-layer audit report follows within 5 business days.
No. All changes are applied in a staging environment and verified against your design and functionality before going live. We document every change so you have full visibility. High-risk changes (like script removal from checkout) are tested against your payment flows before deployment.
Stores starting from a PageSpeed score in the 40s to 70s typically reach the 88 to 97 range after a full four-layer sprint. LCP improvements of 1.5 to 3 seconds are common when the theme and script layers both carry significant debt. The audit will tell you exactly what is realistic for your store before any work begins.
Both, but we prioritize field data. Google's CrUX report reflects what real users experience on real devices and connections. A 96 lab score means nothing if your mobile users on 4G see a 4s LCP. We track CrUX field data before and after every sprint so you see real improvement, not just a better test number.
Yes. Heavily customized stores often have more performance debt than out-of-the-box themes because of accumulated script additions, non-standard Handlebars patterns, and app bloat from years of iteration. We work inside custom themes. The audit will surface the highest-impact changes specific to how your store is built, not a generic template assumption.
Is this the right fit?
Who gets the most from a speed sprint
Speed optimization compounds over time. These stores see the strongest results.
Good fit for...
- Stores with a PageSpeed score below 80 that are losing organic rankings or seeing high bounce rates on mobile
- Merchants who have tried speed apps or manual fixes and not seen lasting results across all pages
- Heavily customized Stencil themes with accumulated script and app overhead from multiple development cycles
- Brands preparing for a seasonal peak who need measurable speed gains before traffic spikes
Not a fit if...
- You want a one-time Lighthouse report with no implementation or sprint work
- Your store is pre-launch or still on a default Stencil theme with no customization
- You're on a platform other than BigCommerce (our tuning is Stencil-specific and won't transfer)
- You need a full theme rebuild before optimization work can have impact
Not sure? Tell us your situation and we will be straight with you. Describe your store →
Get your speed audit
Submit your brief
Tell us about your store and what's slowing you down. We'll review your situation and send a scoped speed audit proposal within 3 business days. No commitment. No pitch.
1
Submit your brief
Takes 3 minutes. No technical knowledge required.
2
Call within 48 hours
We'll ask about your current setup and what's breaking.
3
Audit delivered in 5 days
Full four-layer report with specific, prioritized fixes.
4
Sprint 1 starts within a week of sign-off
First measurable results within 2 weeks.
Scoped before work starts · line-by-line audit · no commitment to receive a proposal
What do you need?
Call within 48 hours · audit in 5 days · Sprint 1 within 1 week of sign-off
Brief received
We'll review your store and send a scoped audit proposal within 3 business days. A team member will reach out within 48 hours to discuss your setup.
Response in 48 hours
Proposal in 3 days
35+ sprints completed
You own all code
No commitment. No pitch.
Every day your store loads slowly, you're handing revenue to a faster competitor.
An audit tells you exactly where the problem is and what it's costing you. There's no obligation to continue after you receive it.
Submit brief → call within 48 hours → audit in 5 days → Sprint 1 within 1 week of sign-off