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Initially I wrote an answer related to PHP part, suggesting the usage of dedicated functions for reading and writing csv, fgetcsv() and fputcsv() respectively, but I didn't test the code. Thanks to @akki who pointed out to some errors and the profiling results, I learned that these functions are dramatically slower, as explained in this answer. A code using then run 20 times slower than the code from the OP.

So we can conclude that the PHP part is already optimized and hardly can be improved performance-wise

Initially I wrote an answer related to PHP part, suggesting the usage of dedicated functions for reading and writing csv, fgetcsv() and fputcsv() respectively, but I didn't test the code. Thanks to @akki who pointed out to some errors and the profiling results, I learned that these functions are dramatically slower, as explained in this answer. It looks like fgetcsv() is 40 times slower than fread/explode. However, to parse the proper csv, with field delimiters and escaping, you have to use the proper function anyway.

Here is the code

<?php

$t = microtime(1);
$i_fp = fopen("inFile.csv","r");
while(!feof($i_fp)) {
    $line = fgets($i_fp);
    $split = explode(';',$line);
}
echo "fgets: ".round(microtime(1)-$t,2)."\n";    
$t = microtime(1);
$i_fp = fopen("inFile.csv","r");
while (($split = fgetcsv($i_fp, 512, ';')) !== FALSE)
{
}
echo "fgetcsv: ".round(microtime(1)-$t,2)."\n";    

outputs for me

fgets: 2.1
fgetcsv: 84.45

on a file with 1 mil rows

As this is a codereview, let's review the PHP part as well.

I doubt these improvements will add a lot of speed but they will definitely add to the main benefits of PHP code - the clarity and conciseness. And the time and effort spent for writing the code to do the job

<?php
$i_fp = fopen("inFile.csv","r");
$o_fp = fopen("outFile.csv","w");

while (($split = fgetcsv($i_fp, 0, ';')) !== FALSE)
{
    if(isset($split[3][0]) && ($split[3][0] == 'E' || $split[3][0] == 'T'))
    {
        fputcsv($o_fp, [
            $split[0], $split[1], $split[3], $split[4], $split[5], $split[6],
            $split[10], $split[9],$split[11],$split[7],$split[32]
        ]);
    }
}

Here we are just using dedicated functions for reading and writing csv, and also omitting the fclose() calls because PHP will happily close all the handlers for us, and also the closing tag as it's usage is discouraged.

Edit: thanks to @akki, several errors have been fixed

Initially I wrote an answer related to PHP part, suggesting the usage of dedicated functions for reading and writing csv, fgetcsv() and fputcsv() respectively, but I didn't test the code. Thanks to @akki who pointed out to some errors and the profiling results, I learned that these functions are dramatically slower, as explained in this answer. A code using then run 20 times slower than the code from the OP.

So we can conclude that the PHP part is already optimized and hardly can be improved performance-wise

As this is a codereview, let's review the PHP part as well.

I doubt these improvements will add a lot of speed but they will definitely add to the main benefits of PHP code - the clarity and conciseness. And the time and effort spent for writing the code to do the job

<?php
$i_fp = fopen("inFile.csv","r");
$o_fp = fopen("outFile.csv","w");

while (($split = fgetcsv($i_fp, 0, ';')) !== FALSE) {
{
    if($split[3] == 'E' || $split[3] == 'T')
    {
        fputcsv($o_fp, [
            $split[0], $split[1], $split[3], $split[4], $split[5], $split[6],
            $split[10], $split[9],$split[11],$split[7],$split[32]
        ]);
    }
}

Here we are just using dedicated functions for reading and writing csv, and also omitting the fclose() calls because PHP will happily close all the handlers for us, and also the closing tag as it's usage is discouraged.

As this is a codereview, let's review the PHP part as well.

I doubt these improvements will add a lot of speed but they will definitely add to the main benefits of PHP code - the clarity and conciseness. And the time and effort spent for writing the code to do the job

<?php
$i_fp = fopen("inFile.csv","r");
$o_fp = fopen("outFile.csv","w");

while (($split = fgetcsv($i_fp, 0, ';')) !== FALSE)
{
    if(isset($split[3][0]) && ($split[3][0] == 'E' || $split[3][0] == 'T'))
    {
        fputcsv($o_fp, [
            $split[0], $split[1], $split[3], $split[4], $split[5], $split[6],
            $split[10], $split[9],$split[11],$split[7],$split[32]
        ]);
    }
}

Here we are just using dedicated functions for reading and writing csv, and also omitting the fclose() calls because PHP will happily close all the handlers for us, and also the closing tag as it's usage is discouraged.

Edit: thanks to @akki, several errors have been fixed