If you recently installed a new ROM, probably CyanogenMod or any other ROM based on CM itself, and are experiencing some delay in notificaitons from Whatsapp or any other such apps, then we have a fix for you. You would need root access for this, something you most probably already have if you are on CyanogenMod. Also, using the root access, you can also fix the low volume sound bug, as all it involves is editing a sound file and provide higher default level of volume.
Let’s see the fix for WhatsApp notification delay now. Well, you need to install an Android app for that, called ‘Root – Push Notification Fixer‘. Open the app, provide it root access, and change two settings.
First, in the app, tap on ‘Mobile heartbeat interval’ and set it to 6 minutes. Second, tap on ‘Wi-Fi heartbeat interval’ and set it to 5 minutes. This should fix the delay. With these settings, ‘push connection’ will be kept more alive than earlier, resulting in faster notifications from WhatsApp and similar apps.
Give your device a reboot, and this should fix the delay in WhatsApp notifications. Let us know how this works out for you.