A GT610 is unlikely to play the game very well.
You can try reducing all settings in-game to their lowest values.
Disable all running programs.
Open up nVidia Control Panel, go to 3D Properties for PvZ2.exe, reduce all the settings you can.
Example of 3D settings off top of my head
Power Management = Max, Texture Filter = Performance/Low, Vsync = off, Single Display mode, AA = Off, Pre-rendered Frames (need to test with it)
You may be able to dive deeper into the game's settings by editing the ini files located in Documents. I do not have any examples off the top of my head for this title yet. If you mess it up, you can delete the Documents files and they will rebuild as default next launch.
*Reduce the resolution the game is in.
** This may or may not work in PvZGW2
Open Notepad.
Copy and Paste this:
RenderDevice.ForceRenderAheadLimit 1
PerfOverlay.DrawGraph 0
PerfOverlay.DrawFps 1
PostProcess.DofMethod 0
PostProcess.BlurMethod 0
PostProcess.DynamicAOEnable 0
PostProcess.DynamicAOMethod 0
Render.VSyncFlashTestEnable 0
WorldRender.TransparencyShadowmapsEnable 0
WorldRender.MotionBlurEnable 0
WorldRender.MotionForceOn 0
WorldRender.SpotLightShadowmapEnable 0
WorldRender.SpotlightShadowmapResolution 256
WorldRender.LightTileCsPathEnable 0
RenderDevice.Dx11Enable 0
RenderDevice.Dx11Dot1Enable 0
RenderDevice.Dx11Dot1RuntimeEnable 0
RenderDevice.VSyncEnable 0
RenderDevice.TripleBufferingEnable 0
GameTime.MaxVariableFps 30
Save it as "user.cfg"
Place this file inside your PvZ:GW2 install folder (i.e. Origin Games usually)
You cannot have user.cfg.txt
enable "View Extentions of Known File Types" from Folder Options in Control Panel
GT610 is pretty far below the requirements. I do not think it'll be possible to get a decent experience out of it.
Sorry