NextGEN Gallery is already an extremely fast gallery plugin for WordPress.
It's also the most robust, which means there are settings which could potentially slow down a site.
In this article, we're going to go over settings which have an impact on performance.
Keep in mind, that none of the settings have a major impact one way or another. But everything together can add up.
Turning on the ability to resize images after upload means you can keep front end displayed images small enough to load fast.
Backup the original images
By backing up your original images at the same time as resizing the displayed images, it means you can always revert your displayed images to the original, to a larger size, remove watermarks and even sell photos based on the backed up image.
Having both resize and backup turned on also means NextGEN Gallery will implement retina images for your site. The result means that people with retina displays will see a much clearer image than if retina images didn't exist. They will see a larger image (double the size) scaled down to the smaller size. Whereas a non-retina display would only show the smaller size at the specific size.
Show related images
The feature to show related images uses a decent amount of server resources for the dynamic matching. Leaving the feature off will save that performance impact.
Applying the Lightbox effect
By applying the lightbox to only NextGEN Gallery, it means that the script for the lightbox will only load on pages or posts that contain a NextGEN Gallery. But if you change the option to use the lightbox in other places, like any images linking to an image, then the lightbox script will load everywhere on your site.
Custom CSS Styles
NextGEN Gallery includes an update safe custom CSS area. Here you have the ability to add custom CSS to modify parts of your displayed galleries. The CSS file, while small, will load on every page of your site. If you are not using custom CSS in that area, turn off the feature to prevent the file from loading.
This is a feature that is rarely used these days, so we recommend leaving it set to No unless you need it.
Galleries in feeds
RSS feeds are becoming less popular these days, so we recommend not having galleries included in feeds. Save on that little performance hit you'd get with the feature turned on.
NextGEN Plus and Pro have image protection features. Turning it on will disable right click and dragging of images in NextGEN Galleries. Once on, there is an option to enable the protection sitewide on all pages. If on, the protection script will load on all pages of your site.
Pagination & Lazy Loading
Some galleries include options for pagination, which comes in multiple formats. Standard pagination will create page numbers which will prevent NextGEN Gallery from loading the images on the other pages until the page is clicked on. Standard pagination will change the URL of the page your gallery is included to show what page you're on.
Ajax pagination is similar but uses scripts to keep the URL as the original, and dynamically load the next page and batch of images.
Lastly is lazy loading which includes infinite scroll. This is like pagination except for the next batch of images as you scroll a page. You can control how many images load initially and how many loads as you scroll.
Using pagination and lazy loading will help speed up the loading times of galleries.
Menu Cart Icon
NextGEN Pro includes an option to display the cart icon (and total value) in the menu. By turning the feature to anything but None, it will load a small cart tracking script on every page of your site.