You may want to run your model through our benchmarking tooling to find what may be causing it.
Local benchmarking:

  
      

      github.com
  

  
    tfjs/e2e/benchmarks/local-benchmark at master · tensorflow/tfjs

  master/e2e/benchmarks/local-benchmark

  A WebGL accelerated JavaScript library for training and deploying ML models.

  

  
    
    
  

  


Browser stack support too:

  
      

      github.com
  

  
    tfjs/e2e/benchmarks/browserstack-benchmark at master · tensorflow/tfjs

  master/e2e/benchmarks/browserstack-benchmark

  A WebGL accelerated JavaScript library for training and deploying ML models.