If you have any graphic editing software such as Adobe Photoshop, you can batch resize the images before uploading. You can use the File > Scripts > Image Processor command in Adobe Photoshop to easily resize an entire folder in 1 step. For resize we suggest 3500 x 3500 pixels. Resized images will upload much faster.
The attached screenshot shows the suggested settings of Image Processor in Photoshop.
If you do not have Photoshop, you can also do batch resize using other softwares including free ones such as IrfanView (http://www.irfanview.com) however the instructions above are for Photoshop. Please make sure that when resizing you do not overwrite the original files and select a new folder for output.
If you have any questions or comments about the above steps, please feel free to send us an email.