My hp elitebook 820 g3 is very slow it has 4GB ram DDR4 2133GHz speed and memory consumed 2.8

[Raymondsiwo]

My hp elitebook 820 g3 is very slow it has 4GB ram DDR4 2133GHz speed and memory consumed 2.8 living 1.1 GB available could it be the problem 

[Paul_Tikkanen]

Yes, with only 4 GB of memory nowadays, that isn't enough anymore.

Your notebook can support up to 2 x 8 GB of DDR4-2133 memory.

HP EliteBook 828 G3 Notebook PCHP EliteBook 820 G3 Notebook PC Maintenance and Service Guide

I would see if you can get this memory in your country and it should perk things up quite a bit.

The DDR4-2400 memory will automatically bridge to 2133 MHz because that is as fast as your notebook's processor can run the memory at.

Timetec 8GB DDR4 2400MHz (DDR4-2400) PC4-19200 (PC4-2400T) Non-ECC Unbuffered 1.2V CL17 1Rx8 Single ...

Also, if your notebook came with a 2.5" mechanical hard drive, I definitely recommend replacing that with a much faster performing M.2 2280 NVMe SSD which is supported in your notebook.

Amazon.com: Crucial P3 Plus 1TB PCIe Gen4 3D NAND NVMe M.2 SSD, up to 5000MB/s - CT1000P3PSSD8 : Ele...

The above SSD is PCIe Gen 4.0 but it costs less than the PCIe Gen 3.0 model.

Since your notebook's M.2 slot is only PCIe Gen 3.0, the Gen 4.0 SSD will not run at its maximum advertised read/write speeds from the Gen 3.0 slot.