読込速度1秒以内を目指して！　計測サイトGTmetrixの表示メッセージと解決のし方

Avoid a character set in the meta tag

<meta charset="utf-8">

<meta http-equiv="content-type" content="text/html; charset=UTF-8">

Avoid bad requests

Avoid CSS @import

Avoid landing page redirects

Combine images using CSS sprites

Defer parsing of JavaScript

Enable gzip compression

Enable Keep-Alive

Inline small CSS

Inline small JavaScript

Leverage browser caching

Minify CSS

Minify HTML

Minify JavaScript

Minimize redirects

Minimize request size

Optimize images

Optimize the order of styles and scripts

Prefer asynchronous resources

Put CSS in the document head

Remove query strings from static resources

function vc_remove_wp_ver_css_js( $src ) {
    if ( strpos( $src, 'ver=' ) )
        $src = remove_query_arg( 'ver', $src );
    return $src;
}
add_filter( 'style_loader_src', 'vc_remove_wp_ver_css_js', 9999 );
add_filter( 'script_loader_src', 'vc_remove_wp_ver_css_js', 9999 );

Serve scaled images

Serve resources from a consistent URL

Specify a cache validator

<IfModule mod_headers.c>
# Cache-Control max-age使用例 1 month
<Files ~ ".(jpg|jpeg|png|gif|ico)$"> 
Header set Cache-Control "max-age=2592000, public">
</Files>

# max-age 1 days
<Files ~ ".(css|js|html|gz)$">
Header set Cache-Control "max-age=86400, public"
</Files>
</IfModule>

Specify a Vary: Accept-Encoding header

# Vary: Accept-Encoding header
<IfModule mod_deflate.c>
Header append Vary Accept-Encoding env=!dont-vary
</IfModule>

Specify a character set early

AddDefaultCharset utf-8

Specify image dimensions

Add Expires headers

Avoid AlphaImageLoader filter

Avoid CSS expressions

Avoid empty src or href

Avoid HTTP 404 (Not Found) error

Avoid URL redirects

Configure entity tags (ETags)

Compress components with gzip

Do not scale images in HTML

Make AJAX cacheable

Make favicon small and cacheable

Make fewer HTTP requests

Make JavaScript and CSS external

Minify JavaScript and CSS

Put CSS at the top

Put JavaScript at bottom

Reduce cookie size

Reduce DNS lookups

<link rel="dns-prefetch" href="//pagead2.googlesyndication.com">
<link rel="dns-prefetch" href="//googleads.g.doubleclick.net">
<link rel="dns-prefetch" href="//www.gstatic.com">

Reduce the number of DOM elements

Remove duplicate JavaScript and CSS

Use a Content Delivery Network (CDN)

Use cookie-free domains

Use GET for AJAX requests