does making new partitions slows down the system during startup ?
no, it won't slow down your system.
simply defragment your hard drive and then use Partition Magic to create a new partition.
but, remember to take a backup of your data before you attempt this.
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Partiton Magig is of course a good option but if you don't want to use a third party software then you can use an alternative method too. RIght click on My Computer->Manage->from the left panel choose Disk Management. There You'll see all the details of your existing partition. Back up (copy) all data temporarily from the partition that you are about to break in two halves to the other existing partition. then right click on the partition that you want to break and select 'Delete Logical Drive'. Once this is done Again right click on the newly created un assigned space; it will give option to form new partition and you can assign the new drive size. Create two seperate drives assigning desired space to each. Next format the two new drives to start using. Don't do this on the system drive.
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