How can I reduce the volume of data (No column to be dropped)?
You are the domain expert on this, but these are the two practical approaches, I have utilized depending on the use case and effect on performance:
1. Downsample: Let say, randomly choose 5,000 out of 80,000 records. To maintain the same proportion of classes as in the population, go for stratified random sampling.
2. Reduce the precision of measurements (i.e. less decimal points) and aggregate data to capture the frequency of similar records as a new feature. If you have repeating records you can do this without compromising on the precision too.