ENH: DataFrame.append is slow when the DataFrame is huge
#### Is your feature request related to a problem?
pandas.DataFrame.append is slow.
Users use DataFrame.append multiple times. And it's more pronounced when the data is huge.
That would take a long time to combine the data.
So some users are using DataFrame.from_dict which is faster than DataFrame.append. (check additional reference)

```python
N = 10000
for i in range(N):
  df = df.append(other, ignore_index=True)
```
#### Describe the solution you'd like

I guess DataFrame.append is slow because there's a copy operation of DataFrame in somewhere.
But I haven't found it yet. 
The solution will be to rewrite the process to be more efficient by not making copies.


#### Additional reference

https://stackoverflow.com/questions/27929472/improve-row-append-performance-on-pandas-dataframes
