Resize your images to decrease their file size. You can use the Photo Gallery app in Windows 8.1 to resize the picture. If you don't have Photo Gallery installed, download it as part of the Windows Essentials software bundle. Alternatively, use an online photo resizing tool.
Press Windows-S to display the Search charm, type Photo Gallery into the search field and click the Photo Gallery app in the list of search results to launch it.
Click File and select Include Folder from the menu to add the folder that contains the image to list of folders. The Pictures Library Locations dialog displays.
Click the Add button to display the Include Folder in Pictures dialog, select the folder you want to include, and then click the Include button. Click OK to close the Pictures Library Locations dialog.
Select the folder that contains the picture from the folders in the left pane. Right-click the image and select Resize from the context menu to display the Resize dialog.
Select a predefined size from the Size drop-down box or provide the Maximum Dimensions.
Photo Gallery resizes the longest side of the picture to the value in the Maximum Dimensions field and resizes the shorter side automatically to maintain the aspect ratio to avoid distorting the image.
Click Resize and Save. A new picture is created in the same folder, so saving does not overwrite the original image.