Archer A7 speed

I have 1GB internet if I use openWrt on my TP-Link Archer A7 will I retain my speed

No, its CPU is not fast enough.

What does cpu have to do with internet speed.
When you look at this product on Amazon it says it will do 1300mbps on 5ghz.
That’s with original tp link software installed.
I would’ve thought openwrt would be less cpu stress then tp links own software

The Archer A7 v5 has a single-core mips 74Kc based QCA9563 SOC, running at a clockspeed of 750 MHz. The performance of this 750 MHz (mips 74Kc router-) CPU is good for around 200 MBit/s (give or take) WAN-LAN routing/ NAT in software, it's utterly insufficient to handle 1 GBit/s WAN speeds.

TP-Link AC1750 Wireless Dual Band Full Gigabit Wi-Fi Router, Wi-Fi Speed Up to 1300 Mbps/5 GHz + 450 Mbps/2.4 GHz, With1 x USB2.0 Port, Qualcomm CPU, Supports Parental Control, Easy setup (Archer A7)

So this is wrong then

I connected my pc to the tp link router yesterday, these are my speed results…

I was hoping openWrt would run smoothly on it as I’ve wanted to setup an openvpn using my vpn provider.