fps = 4, 100% CPU utilisation,
Operating System: Kubuntu 19.04
KDE Plasma Version: 5.15.4
KDE Frameworks Version: 5.56.0
Qt Version: 5.12.2
Kernel Version: 5.0.0-38-generic
OS Type: 64-bit
Processors: 4 × AMD Phenom(tm) 9850 Quad-Core Processor
Memory: 7.8 GiB of RAM
3D Accelerator Device Cedar [Radeon HD 5000/6000/7380/8350 Series]
Driver AMD CEDAR (DRM 2.50 / 5.050-generic, LLVM 8.0.0)
Problem has not reoccurred since I reduced the render distance down to some thing reasonable (12 blocks) to more closely match the server.
Logs attached in previous comment.
Adding the shader resource pack increased the fps from 3-5 to 14-16 and presented a mostly black screen.
This error also occurred:
04:06:25.407
Could not find uniform named InSize in the specified shader program.
Turning off the clouds resolved the cloud issue.