BigCommerce Speed Optimisation: Make Your Store Load in Under 2 Seconds

BigCommerce Speed Optimisation: The Sub-2-Second Store

Every 100ms of latency costs approximately 1% in conversion rate. For a store generating $1M annually, a one-second improvement in load time could mean $70,000+ in additional revenue. Here is how to make your BigCommerce store blazingly fast.

Measuring Current Performance

Before optimising, establish baselines:

• Google PageSpeed Insights: Overall performance score and Core Web Vitals
• WebPageTest: Detailed waterfall analysis from multiple locations
• Chrome DevTools: Network panel for request-level timing
• Real User Monitoring: Actual performance data from customer browsers

Core Web Vitals Targets

Image Optimisation

Images typically account for 50-70% of page weight:

Format Selection

• Use WebP as the primary format with JPEG fallback
• Use AVIF for browsers that support it for even smaller files
• Use SVG for logos, icons and simple graphics
• Never use PNG for photographs

Sizing and Loading

• Serve responsive images using srcset attributes
• Implement lazy loading for below-fold images
• Set explicit width and height to prevent layout shift
• Use BigCommerce image manager for automatic resizing

Product Images

• Compress product images to under 100KB each
• Use consistent aspect ratios to prevent CLS
• Preload the first product image on listing pages
• Serve thumbnail sizes for category grids

JavaScript Optimisation

Audit Third-Party Scripts

Every app and integration adds JavaScript:

• List all scripts loading on each page template
• Identify scripts that block rendering
• Defer non-critical scripts to load after page content
• Remove scripts from apps you no longer use

Script Loading Strategy

• Critical scripts: Load inline or with high priority
• Important scripts: Load with defer attribute
• Analytics and tracking: Load after page interaction
• Chat widgets: Load on scroll or after 5 seconds

CSS Optimisation

Critical CSS

Inline CSS needed for above-fold content:

• Extract critical CSS for each page template
• Inline in the head for instant rendering
• Load remaining CSS asynchronously
• Remove unused CSS rules from theme files

Font Loading

Fonts often block text rendering:

• Use font-display: swap for all web fonts
• Preload critical font files
• Limit font weights and variants to those actually used
• Consider system fonts for body text

Server and CDN

BigCommerce CDN

Maximise CDN effectiveness:

• Ensure all static assets load from CDN
• Set appropriate cache headers for static content
• Use cache-busting for updated assets
• Configure edge locations closest to your customer base

Prefetching

Anticipate user navigation:

• Prefetch product pages on category listing hover
• Preconnect to third-party domains used on the page
• DNS-prefetch for domains used later in the journey

Theme Optimisation

Template Efficiency

• Minimise Handlebars template complexity
• Reduce the number of partial includes per page
• Cache computed values in template variables
• Remove unused template sections

Asset Pipeline

• Concatenate and minify all CSS and JavaScript
• Enable Gzip or Brotli compression
• Implement code splitting for page-specific scripts
• Use tree shaking to remove dead code

App Performance Audit

Conduct quarterly app performance reviews:

• Disable each app individually and measure speed impact
• Identify apps loading scripts on pages where they are not needed
• Contact app developers about performance concerns
• Replace heavy apps with lighter alternatives or custom code

Performance Monitoring

Set up ongoing monitoring:

• Real User Monitoring for actual customer experience data
• Synthetic monitoring for consistent benchmark tracking
• Alerting for performance regressions
• Monthly reporting comparing speed to conversion metrics

Performance Budget

Establish limits for your team:

• Total page weight: under 1.5MB
• Total requests: under 50
• JavaScript payload: under 300KB
• Time to Interactive: under 3 seconds

Globify provides BigCommerce performance optimisation services that deliver measurable speed improvements and conversion gains. Contact us for a performance audit.