[BUG] PerformanceWarning DataFrame is highly fragmented.

Requirements (place an `x` in each of the `[ ]`)**

[ x] I realize finplot is not a web lib. (Hint: it's native!)
[ x] I've read the snippets and not found what I'm looking for.
[ x] I've searched for any related issues and avoided creating a duplicate issue.
[ x] I've updated finplot (pip install -U finplot).
[ x] I've supplied the required data to run my code below.

Code to reproduce

import finplot as fplt
import pandas as pd

def create_chart(self):
        self.add_hh_ll_hl_lh_labels()
        self.add_buy_entries()
        self.add_trade_boxes()
        self.add_trend()
        fplt.lod_labels = 200
        self.add_news_labels()
        if self.realtime:
            fplt.timer_callback(self.update_data, 3.0)
        fplt.show()

def update_data(self):
        """
        Updates the data by reading a CSV file, converting the date column to datetime,
        resetting the index, and renaming the index column.
        """
        script_dir = os.path.dirname(os.path.realpath(sys.argv[0]))
        parent_dir = os.path.dirname(script_dir)
        data_file_path = os.path.join(parent_dir, 'BackEnd', 'data.csv')
        with open(data_file_path, 'r') as f:
            self.df = pd.read_csv(f)
        self.df['date'] = pd.to_datetime(self.df['date'], errors='coerce')
        self.df['date'] = self.df['date'].astype('int64')
        self.df.reset_index(inplace=True)
        self.df.rename(columns={'index': 'Unnamed: 0'}, inplace=True)
        self.plot_candles.candlestick_ochl(
            self.df[['date', 'open', 'close', 'high', 'low']])
        self.add_hh_ll_hl_lh_labels()
        self.add_trend()
        self.add_news_labels()
        self.add_buy_entries()
        self.add_trade_boxes()

Describe the bug

When trying to use the realtime method what I do is that i have in the background a process that updates a csv file every x seconds. And using finplot I am reading the csv file using the timer_callback method which will use the update_data method.

after some time i get this error:

/opt/homebrew/lib/python3.11/site-packages/finplot/init.py:442: PerformanceWarning: DataFrame is highly fragmented. This is usually the result of calling frame.insert many times, which has poor performance. Consider joining all columns at once using pd.concat(axis=1) instead. To get a de-fragmented frame, use newframe = frame.copy() output_df[col] = df[col]

Is there a better way to do it without any performance sacrifice ?

Reproducible in:

OS: Mac OS finplot version: 1.9.5 pyqtgraph version: 0.13.3 pyqt version: PyQt6

highfestiva / finplot