Tech giant Apple is facing a class-action lawsuit. iPhone 4S users were allegedly misled by the company that the unit is compatible with the latest iOS 9 update.

A suit filed by Chaim Lerman including 100 others claims that Apple's latest iOS 9 update slowed down their iPhone 4S third-party app and core functionality performance. The claimants further said that the company's latest update degraded their phones' efficiency and did not forewarn users about it.

Instead of Apple's promise that the new operating system will fasten performance, improve security, ease updates and prolong battery life as posted on its website, its smartphones have allegedly disrupted their everyday life and become "inoperable." And because the update cannot be reversed, the plaintiffs point only two possible solutions -- either to deal with the slow phone or to allocate hundred of dollars and get the latest, or newer, iPhone that is compatible with the latest iOS. 

"Plaintiff and other owners of the iPhone 4S were harmed when their devices's software was updated to the newest version, iOS 9... The update significantly slowed down their iPhones and interfered with the normal usage of the device," the lawsuit reads.

Lerman officially filed his complaint on Dec. 29 at a New York district court on a ground that the tech giant has been deceptive and falsely advertising that its latest operating system is compatible with older iPhone versions. iPhone 4S users are demanding over $5 million for the damages incurred.

This is not the first time Apple received lawsuits against performance issues. Last October, the company was dragged to court because its Wi-Fi Assist feature costs several users a lot of money after the phone automatically switches from Wi-Fi network to cellular network when the connection detected is poor. Also, Apple was also sued for the size of storage its iOS takes, making those users with only 8GB or 16GB capacity difficult to update.