What is the disadvantage of using firewall in pc?

I personally feel that it is very essential to run a firewall on your PC. The only point of inconvenience that I can recall is to manually open up ports if you were to host services for other hosts over the network.

sometimes it hinders installation of highly customised products 

system performance degradtion

The Windows Firewall does a good job of proxying inbound responses to outbound connection requests, and it does a good job of blocking inbound connection requests for TCP or UDP conversations that you haven't initiated. It will block any connection attempts that you haven't specifically allowed in the settings. Firewall means security and the cost of security is the delay.

the firewall might add some delay to inspect all inbound and outbound traffic. on the other hand some false positive alarms might block some applications.

Degrade System Performance (Resource Utilization to check every packet data)

PC Resource Utilization ; als packet inspection technique won't be as effecient as deditcated firewall 

Packet filtering by a software firewall can degrade your pc performance, because it's a demanding task to examine every packet of data. A hardware firewall eases this burden from every PC in the network to a centrilized solution.

limited protection 

utilize PC resources

managment issues 

firewall on pc like Gard in your house that has 65535 doors it checks everything pass through the doors to be safe but it takes time for check and processing

Even if a firewall helps in keeping the network safe from intruders, but if a firewall is not used properly it would give a false impression to you that the network is safe. The main disadvantage of a firewall is that it cannot protect the network from attacks from the inside.

They often cannot protect against an insider attack.

Firewalls cannot protect a network or pc from viruses, Trojans, worms, and spyware which spread through flash drives, portable hard disk, and floppy etc.

They may restrict authorized users from accessing valuable services.

They do not protect against backdoor attacks.

When the packets are filtered by software firewall, the system's performances degrades. Also it allows users to think that they can access any sites as there is a firewall which would protect them, but if it fails, security is at risk.