Slow deletes if number of deleted rows smaller then LIMIT

Have two tables RLOG, RREC which basically Looks like this:

CREATE TABLE rrec (

  RREC_TIMESTAMP_DT varchar(25) NOT NULL,

  RREC_SESSION_UID varchar(70) NOT NULL,

  ... (shorten) ...

  PRIMARY KEY (RREC_SESSION_UID),

 ...

    )

ENGINE = INNODB

AVG_ROW_LENGTH = 197

CHARACTER SET latin1

COLLATE latin1_general_cs

ROW_FORMAT = COMPRESSED;

and

CREATE TABLE rlog (

  RLOG_ID varchar(70) NOT NULL,

  RLOG_LOGENTRY longtext DEFAULT NULL,

  PRIMARY KEY (RLOG_ID),

  UNIQUE INDEX IDX_UK_rlog (RLOG_ID),

  CONSTRAINT RLOG_RREC_FK FOREIGN KEY (RLOG_ID)

  REFERENCES rrec (RREC_SESSION_UID) ON DELETE CASCADE ON UPDATE CASCADE

)

ENGINE = INNODB

AVG_ROW_LENGTH = 2343

CHARACTER SET latin1

COLLATE latin1_general_cs

ROW_FORMAT = COMPRESSED;

(see attachments for full table creation SQL)

Both tables have several rows:

RLOG: 1 MIO
RREC: 1,3 MIO

From time to time i want to delete some entrys from RLOG table:

 DELETE FROM RLOG WHERE RLOG_ID in (SELECT RREC_SESSION_UID FROM RREC WHERE RREC_TIMESTAMP_DT < '2016-01-01') LIMIT 1000;

As long as at least 1000 rows are deleted everything is fine:

1000 rows deleted [0,107s]

but if i delete less then 1000 rows the delete Operation takes very long time:

847 rows deleted [24,270s]

and even worse if nothing is deleted it takes Long time also:

0 rows deleted [24,090s]

Profiling of such a statement shows the following:

updating |51,634785 |99,86|
query end |0,033120 |0,06|
statistics |0,014102 |0,03|
end |0,009650 |0,02|
Unlocking tables |0,005223 |0,01|
freeing items |0,003979 |0,01|
updating status |0,001728 |0,00|
starting |0,001212 |0,00|
init |0,001178 |0,00|
Opening tables |0,000821 |0,00|
preparing |0,000791 |0,00|
closing tables |0,000760 |0,00|
After opening tables |0,000380 |0,00|
checking permissions |0,000288 |0,00|
Table lock |0,000227 |0,00|
cleaning up |0,000024 |0,00|
System lock |0,000020 |0,00|
optimizing |0,000013 |0,00|

If you like I can provide you my testdata (6GB).