Q: slow loading

See:

Mac Maintenance Quick Assist,
Mac OS X speed FAQ,
Speeding up Macs,
How to Speed up Macs,
Macintosh OS X Routine Maintenance,
Mac troubleshooting: What to do when your computer is too slow,
Essential Mac Maintenance: Get set up,
Essential Mac Maintenance: Rev up your routines,
Maintaining OS X, 
Five Mac maintenance myths and
Myths of required versus not required maintenance for Mac OS X for information.

BTW, iOS info is useless, put down which OS X you're running.

We really need a lot more info about your iMac than just posting your iMac is slow.

What year, screen size, CPU speed and amount of RAM installed?

What version of OS X is your iMac running?

How full is your Mac's hard drive?

To find this info, locate the hard drive icon on your OS X desktop.

Click once with your mouse and the use the keyboard key combination Command-I.

How many applications do you run simultaneously in the background while working in another application?

How many tabs or windows do you leave open when using a web browser?

Do you run any antivirus software on your Mac? Antivirus software can slow down the normal operation of OS X.

Do you run any "crapware" like Mackeeper or any other type of "crapware" like so called hard drive "cleaning" apps?

If you do not know where to find this info about your iMac, To find out info about your system, click on the Apple symbol in the upper left of the OS X main menu bar.

A drop down menu appears.

Click About this Mac.

A smaller popup window appears.

This gives you basic info like what version of OS X your iMac is running, the speed of your iMac's CPU and how much RAM is installed.

Click on the button that says More Info.

A larger window appears giving you a complete overview of your iMac's hardware specs.

Highlight all of this info and copy/paste all of this into another reply to this post, editing out your iMac's serial number before actually posting the reply. This will tell us everything about your iMac so we may begin to help with your iMac issues.